Is and isn’t wrong to demand (6)
I believe the answer is:
insist
'demand' is the definition.
(I've seen this before)
'is and isn't wrong' is the wordplay.
'and' says to put letters next to each other (I've seen this in other clues).
'wrong' is an anagram indicator.
'is' after 'isnt' is 'isntis'.
'isntis' anagrammed gives 'INSIST'.
'to' is the link.
(Other definitions for insist that I've seen before include "Beg persistently and urgently" , "Maintain persistently" , "Maintain firmly" , "Continue to assert, maintain" , "Put one's foot down" .)