Member of scrum supports midweek match (7)
I believe the answer is:
wedlock
'match' is the definition.
(thesaurus)
'member of scrum supports midweek' is the wordplay.
'member of scrum' becomes 'lock' (lock is a type of rugby player).
'supports' says to put letters next to each other (bottom letters provide a support for the top ones).
'midweek' becomes 'wed' (short for Wednesday).
'lock' put after 'wed' is 'WEDLOCK'.
(Other definitions for wedlock that I've seen before include "Marital state" , "A state of union" , "The married state - throw away the key" , "Matrimony" , "State of marriage" .)