A company have a DW (Word(s) with device) trade mark "ABC Defghi".
With this type of trade mark which is not a WO (Word(s) only mark) are
the company allowed to separate the word 'Defghi' out from the
complete mark and claim rights over that mark?

To include a reference to substantiate the answer given.

Here is an aswer under US law--I feel certain the UK laws are similar.

If you have a US registration on a "Words and Design" mark and you
extract only the words portion and try to use that as a separate mark,
you may lose the effect of the registration as to the word component
only if you have not sought and obtained a separate registration on
the words standing alone (a "Word Mark registration.")  It depends on
how different the words standing alone are taken apart from the "words
and Design" registered mark.  Does the design component predominate
over the words?  Are the words the registered mark's preeminent
feature?  In other words, could a judge, looking at the words standing
alone and apart from the registered "Design and Words" mark, still
feel that the words alone are similar enough to the registration as
issued such that the words standing alone merit protection?

Let me try this again:

Here is an answer under US law--I feel certain that UK laws are similar.

If you have a US registration on a "Words and Design" mark and you
extract only the words portion and try to use that as a separate mark,
you may lose the effect of the registration as to the word component
if you have not sought and obtained a separate registration on
the words standing alone (a "Word Mark registration").  But it depends
on several factors, like how different the words standing alone are
taken apart from the "Words and Design" registered mark.  Does the
design component predominate over the words?  Are the words the
registered mark's preeminent
feature?  In other words, could a judge, looking at the words standing
alone and apart from the registered "Design and Words" mark, still
feel that the words alone are similar enough to the registration as
issued such that the words standing alone merit protection?  It also
depends on if the words are generic or if they merit trademark
protection in their own right.

Assume you have a logo that uses the words ?Zorgon Upsa? as a
trademark for golf balls, and the words are depicted in a fanciful
script inside a pretty drawing with a sunset and a waterfall and trees
and a lake.  Further assume that this whole logo is a registered
?Design and Words? mark.  If the owner of the mark pulls out the words
?Zorgon Upsa? and places them on a golf ball without the other design
elements, has trademark protection been lost?  Doubtful.  What if he
pulls out the word ?Upsa??  Hmmm, less clear.  How about just the
letter ?U??  Well, clearly that would not have the protection of the
registration.  Now assume that instead of  ?Zorgon Upsa,? you have the
words ?golf balls.?  On those facts, the ONLY reason they are even
protected is because of the design elements, and if you pull those out
of the mark and put them on a golf ball, well, there?s no protection
for generic words!

Further assume that in the registration the words "Zorgon Upsa" are in
a very small font and are very hard to see.  If you pull them out and
use them alone, are they still protected?  Not likely, since they are
not the predominant component of the registered mark.