The fish hawk's outsize prey (6)

I believe the answer is:

osprey

'the fish hawk's' is the definition.
('osprey' can be a synonym of 'fish hawk')

'outsize prey' is the wordplay.
'outsize' becomes 'os'.
'os'+'prey'='OSPREY'

(Other definitions for osprey that I've seen before include "Bird from an outsize victim" , "I grab fish" , "Lakeland bird" , "Flyer" , "Spy roe (anag)" .)

I've seen this clue in the Evening Standard.

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