Duck small victim for large bird (6)
I believe the answer is:
osprey
'large bird' is the definition.
(large bird of prey)
'duck small victim' is the wordplay.
'duck' becomes 'o' (resembles zero - 'duck' in cricket).
'small' becomes 's' (abbreviation - e.g. clothes size).
'victim' becomes 'prey' (prey is a kind of victim).
'o'+'s'+'prey'='OSPREY'
'for' is the link.
(Other definitions for osprey that I've seen before include "Large bird that preys on fish in inland waters" , "Fish-eating raptor" , "Fish-eater" , "Marine bird of prey" , "Bird of fine feather" .)