Love affair within a limit (9)
I believe the answer is:
adoration
'love' is the definition.
(to adore someone is to love them)
'affair within a limit' is the wordplay.
'affair' becomes 'do' (do is a kind of affair).
'within' means one lot of letters goes inside another.
'limit' becomes 'ration' (rationing is a kind of limiting).
'a'+'ration'='aration'
'do' inserted within 'aration' is 'ADORATION'.
(Other definitions for adoration that I've seen before include "Honour" , "Deep love and respect" , "enormous respect" , "What star gets from fans" , "high esteem" .)