Very large quarry for hawk (6)
I believe the answer is:
osprey
'hawk' is the definition.
(osprey is a kind of hawk)
'very large quarry' is the wordplay.
'very large' becomes 'os' (abbreviation for oversize).
'quarry' becomes 'prey' (synonyms).
'os'+'prey'='OSPREY'
'for' is the link.
(Other definitions for osprey that I've seen before include "Bird from an outsize victim" , "Bird of fine feather" , "predatory bird" , "Flier" , "Fish-eating hawk" .)