Very large award set to be reduced (5)
I believe the answer is:
obese
'very large' is the definition.
(I've seen this before)
'award set to be reduced' is the wordplay.
'award' becomes 'OBE' (Order of the British Empire).
'set to' becomes 'set' (synonyms).
'be reduced' means to remove the last letter.
'set' with its last letter taken away is 'se'.
'obe'+'se'='OBESE'
(Other definitions for obese that I've seen before include "Having excessive girth" , "likely to tip the balance?" , "Needing to lose weight" , "Falstaffian" , "Pathologically fat" .)