Fruit — a number outside broken crate (9)
I believe the answer is:
nectarine
'fruit' is the definition.
(nectarine is a kind of fruit)
'a number outside broken crate' is the wordplay.
'a number' becomes 'nine' (nine is a kind of number**).
'outside' is an insertion indicator.
'broken' indicates anagramming the letters.
'crate' anagrammed gives 'ectar'.
'nine' going around 'ectar' is 'NECTARINE'.
(Other definitions for nectarine that I've seen before include "Smooth-skinned variety of peach" , "Trace nine to a kind of peach" , "Entrance I make with thin-skinned peach" , "Fruit - aren't nice (anag)" , "Peach-like fruit" .)