What broke the antler? A bush? (8)
I believe the answer is:
hawthorn
'a bush?' is the definition.
(hawthorn is a kind of bush)
'what broke the antler?' is the wordplay.
'broke' indicates anagramming the letters.
'the antler?' becomes 'horn' (horn on a deer).
'what' with letters rearranged gives 'hawt'.
'hawt'+'horn'='HAWTHORN'
(Other definitions for hawthorn that I've seen before include "Spring-flowering shrub" , "plant" , "May-flowering small tree" , "Spring-flowering small tree with small dark red fruit" , "Small spring-blooming tree" .)