Sense change so near (6)
I believe the answer is:
reason
'sense' is the definition.
(I've seen this before)
'change so near' is the wordplay.
'change' indicates an anagram.
'so'+'near'='sonear'
'sonear' with letters rearranged gives 'REASON'.
(Other definitions for reason that I've seen before include "Cause - logic" , "Cause; think logically" , "Mental power to justify an act" , "Justification or motive" , "Justification; sanity" .)