Agreement with clubs working? Sure thing (7)
I believe the answer is:
concert
'agreement' is the definition.
(thesaurus)
'with clubs working? sure thing' is the wordplay.
'with' means one lot of letters go next to another.
'clubs' becomes 'c' (abbreviation used in card games such as bridge).
'working?' becomes 'on'.
'sure thing' becomes 'cert' (I've seen this before).
'c' next to 'on' is 'con'.
'con'+'cert'='CONCERT'
(Other definitions for concert that I've seen before include "Some entertainment" , "Harmony, performance" , "Harmony of people's opinions, actions or characters" , "Musical performance" , "Public performance of music" .)