Apart and sure to be different (7)
I believe the answer is:
'apart' is the definition.
(I know that apart can be written as asunder)
'and sure to be different' is the wordplay.
'to be different' indicates an anagram (I've seen 'is different' mean this).
'andsure' with letters rearranged gives 'ASUNDER'.
(Other definitions for asunder that I've seen before include "(Torn) into parts" , "bits?" , "(Split) apart" , "being in two" , "Into parts or pieces" .)