Composer’s lark, for example, heard (4)
I believe the answer is:
byrd
'composer's' is the definition.
(Renaissance composer William Byrd)
'lark for example heard' is the wordplay.
'lark for example' becomes 'bird' (lark is a type of bird).
'heard' indicates a 'sounds like' (homophone) clue.
'bird' is a homophone of 'BYRD'.
(Other definitions for byrd that I've seen before include "Prolific scorer" , "Mass producer" , "Old scorer" , "Composer of church music" , "William ---, Tudor composer" .)