Put a stop to golf after the girl's affair (7)
I believe the answer is:
shebang
'affair' is the definition.
('shebang' can informally refer to a matter or situ)
'put a stop to golf after the girl's' is the wordplay.
'put a stop to' becomes 'ban'.
'golf' becomes 'g' (phonetic alphabet: alpha, bravo, charlie etc.).
'after' says to put letters next to each other.
'the girl' becomes 'she' (**).
'ban'+'g'='bang'
'bang' put after 'she' is 'SHEBANG'.
(Other definitions for shebang that I've seen before include "(Whole) kit and caboodle" , "Lot" , "Whole affair" , "The whole thing?" , "The whole ___ (entirely)" .)