Award huge coach (5)
I believe the answer is:
oscar
'award' is the definition.
(an Academy Award)
'huge coach' is the wordplay.
'huge' becomes 'os' (abbreviation for outsize).
'coach' becomes 'car' (as in a train coach or car).
'os'+'car'='OSCAR'
(Other definitions for oscar that I've seen before include "Annual film award" , "Boy" , "Man" , "Cinema award" , "Film acting award" .)