Unity might make no sense (7)
I believe the answer is:
oneness
'unity' is the definition.
(I know that unity can be written as oneness)
'might make no sense' is the wordplay.
'might make' indicates an anagram (the letters might make if rearranged).
'no'+'sense'='nosense'
'nosense' anagrammed gives 'ONENESS'.
(Other definitions for oneness that I've seen before include "Singular quality" , "Unified state" , "Uniqueness" , "single state" , "Singular state" .)