Fruit, fine (not half!) — certain to be reordered (9)
I believe the answer is:
nectarine
'fruit' is the definition.
(nectarine is a kind of fruit)
'fine not half certain to be reordered' is the wordplay.
'not half' means to take half the letters.
'to be reordered' indicates anagramming the letters (I've seen 'reorder' mean this (I've seen this in other clues)).
'fine' halved is 'ne'.
'certain' is an anagram of 'ctarine'.
'ne'+'ctarine'='NECTARINE'
(Other definitions for nectarine that I've seen before include "fruity" , "Variety or mutation of a peach" , "Fruit - aren't nice (anag)" , "Trace nine to a kind of peach" , "type of tree" .)