Huge quarry for fish hawk (6)
I believe the answer is:
osprey
'fish hawk' is the definition.
(synonyms)
'huge quarry' is the wordplay.
'huge' becomes 'os' (abbreviation for outsize).
'quarry' becomes 'prey' (synonyms).
'os'+'prey'='OSPREY'
'for' acts as a link.
(Other definitions for osprey that I've seen before include "Large bird that fishes inland waters" , "The fishing eagle" , "Large bird that preys on fish in inland waters" , "Bird from an outsize victim" , "Large bird preying on fish in inland waters" .)