Coop came good finally with single large clutch? (5)
I believe the answer is:
pedal
'clutch?' is the definition.
(clutch is a kind of pedal)
'coop came good finally with single large' is the wordplay.
'finally' suggests the final letters.
'with' is a charade indicator (letters next to each other).
'single' becomes 'a'.
'large' becomes 'l'.
The final letters of 'coop came good' are 'ped'.
'ped'+'a'+'l'='PEDAL'
(Other definitions for pedal that I've seen before include "Of or relating to the feet" , "work with press from Oxford?" , "Foot-lever" , "cause a revolution in cycling?" , "part of organ" .)