Axe used by a boy on a bird of prey (8)
I believe the answer is:
tomahawk
'axe' is the definition.
(I've seen this before)
'a boy on a bird of prey' is the wordplay.
'a boy' becomes 'tom' ().
'on' is a charade indicator (letters next to each other).
'bird of prey' becomes 'hawk' (hawk is a kind of bird of prey).
'tom'+'a'+'hawk'='TOMAHAWK'
'used by' acts as a link.
(Other definitions for tomahawk that I've seen before include "Amerindian hatchet" , "War hatchet once wielded by native Americans" , "Axe as weapon" , "intended to make a kill" , "Native American weapon" .)