Puzzle bringing no new benefit (7)
I believe the answer is:
nonplus
'puzzle' is the definition.
('nonplus' can be a synonym of 'puzzle')
'no new benefit' is the wordplay.
'new' becomes 'n'.
'benefit' becomes 'plus' (I've seen this before).
'no'+'n'+'plus'='NONPLUS'
'bringing' is the link.
(Other definitions for nonplus that I've seen before include "Perplex totally" , "Get confused" , "Get flummoxed" , "Disconcert, confound" , "stump" .)