...to decline an award (7)
I believe the answer is:
atrophy
'to decline' is the definition.
(I've seen this before)
'an award' is the wordplay.
'an' becomes 'a'.
'award' becomes 'trophy' (trophy is a kind of award).
'a'+'trophy'='ATROPHY'
(Other definitions for atrophy that I've seen before include "Decay" , "wasting away" , "Waste away, wither" , "Waste away - sounds like a sporting award" , "Decline" .)