Sing works by composer, a beat pioneer (8)
I believe the answer is:
ginsberg
'a beat pioneer' is the definition.
(pioneering poet of the beat generation)
'sing works by composer' is the wordplay.
'works' is an anagram indicator (work can mean to twist or convulse).
'by' says to put letters next to each other.
'composer' becomes 'berg' (20th Century Austrian composer).
'sing' with letters rearranged gives 'gins'.
'gins'+'berg'='GINSBERG'
(Other definitions for ginsberg that I've seen before include "Barge" , "Allen ..., US poet of the Beat Generation" .)