The suit is in the bag (4)
I believe the answer is:
case
This clue is a double definition.
'the suit' is the first definition.
(synonyms)
'the bag' is the second definition.
(I have seen 'Overnight bag' mean 'case' so perhaps 'bag' could also mean 'case')
'is in' is the link.
(Other definitions for case that I've seen before include "Instance - container" , "Wine buyer's basic quantity" , "Legal action; box of wine" , "Overnight bag" , "See 12" .)