Doctor sees non-unity? (7)
I believe the answer is:
oneness
'unity?' is the definition.
(I know that oneness can be written as oneness)
'doctor sees non' is the wordplay.
'doctor' indicates anagramming the letters.
'sees'+'non'='seesnon'
'seesnon' is an anagram of 'ONENESS'.
(Other definitions for oneness that I've seen before include "Unity" , "Identity" , "Singular quality" , "#Unique quality" , "Uniqueness" .)