what is the name of the song or score and (who wrote it)?...that is
played in movie true romance in the seen where Clarence (Christian
Slatter) goes to the pimps pad to get dallas's belongings and shoots
the pimp. who wrote it?, what is the name of it?, and where can i purchase the song?

Hello.

I believe that you're thinking of "I Want Your Body" by Nymphomania.

According to a message posted on the Tarantino Archives messageboard,
the song in the scene where Drexl (the pimp played by Gary Oldman) is
killed is a "techno track."
See:
"...The Music? C'mon the techno track in the Kill Drexl [scene] was great..." 
http://tarantino.webds.de/cgi-bin/tarantino/yabb/YaBB.cgi?board=other;action=display;num=1071528765

The "techno track" is apparently "I Want Your Body" by Nymphomania,
according to this newsgroup message, archived by Google groups:

"The Nymphomania is great (it's the house music where Oldman & Slater
duke it out)..."
http://groups.google.com/groups?hl=en&lr=&ie=UTF-8&selm=60.1035.4609.0N18EEC1%40canrem.com&prev=/groups%3Fq%3D%2522True%2Bromance%2522%2Boutshined%2Btechno%26hl%3Den%26lr%3D%26ie%3DUTF-8%26selm%3D60.1035.4609.0N18EEC1%2540canrem.com%26rnum%3D1

This is confirmed in this listener review on Amazon.com:

"Also, I liked the "I Want Your Body" tune by Nymphomania during the
wild scene to retrieve Arizona's clothes ."
http://www.amazon.com/exec/obidos/tg/detail/-/B0000042N2/

The track "I Want Your Body" by Nymphomania is on the True Romance
soundtrack CD listed on Amazon above, or from Tower Records.
http://www.towerrecords.com/product.aspx?pfid=1056929

You could also buy the song as a single from these dealers listed on MusicStack:
http://www.musicstack.com/tsearch/nymphomania/i_want_your_body

-------------
search strategy:
"true romance" pimp
"true romance" "drexl gets"
"true romance" nymphomania scene

I hope this is the song that you had in mind.  If not, please let me
know via the "request clarification" feature. Thank you.

Great Response Time And Complete

Thank you for the tip.
-juggler