Deceive with trick to ensnare heart -- not right! (5,2)
I believe the answer is:
cheat on
'deceive' is the definition.
(cheating on is a kind of deceiving)
'trick to ensnare heart not right' is the wordplay.
'trick' becomes 'con' (I've seen this before).
'to ensnare' is an insertion indicator.
'not' indicates named letters should be taken away.
'right' becomes 'r' (common abbreviation).
'heart' with 'r' removed is 'heat'.
'con' enclosing 'heat' is 'CHEAT ON'.
'with' is the link.
(Another definition for cheat on that I've seen is " Be unfaithful to one's partner".)