No more - it's enough to perplex (7)
I believe the answer is:
nonplus
'to perplex' is the definition.
('nonplus' can be a synonym of 'perplex')
'no more' is the wordplay.
'no' becomes 'non' (I've seen this in other clues).
'more' becomes 'plus' (I've seen this before).
'non'+'plus'='NONPLUS'
'it's enough' is the link.
This may not be right. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for nonplus that I've seen before include "Perplex totally" , "Floor" , "Flummox" , "Cause dismay" , "Confound, bewilder" .)