Businessman's clubs? (4)
I believe the answer is:
suit
This clue is a double definition.
'businessman's' is the first definition.
'clubs?' is the second definition.
(clubs is an example of a card suit)
(Other definitions for suit that I've seen before include "Legal action - courtship" , "Complement" , "Set of cards" , "Quarter of a full deck" , "Case < for outfit" .)