Composer contributing to squalid revue after reflection (5)
I believe the answer is:
verdi
'composer' is the definition.
(I've seen this before)
'contributing to squalid revue after reflection' is the wordplay.
'contributing to' indicates the answer is hidden within the clue.
'after reflection' is a reversal indicator.
'idrev' is hidden within 'squalid revue'.
'idrev' written backwards gives 'VERDI'.
(Other definitions for verdi that I've seen before include "Drive around with great opera composer" , "Drive around to locate opera composer" , "Giuseppe -----, 1813-1901, prolific opera composer" , "Drive (anag) - composer" , "Composer of opera ''Rigoletto''" .)