Joker Jack, say? (4)
I believe the answer is:
card
I believe this is a double definition.
'joker' is the first definition.
(joker is a type of playing card)
'jack say?' is the second definition.
(jack is a type of playing card)
(Other definitions for card that I've seen before include "Stiff paper; comb" , "caution" , "programme at race meeting" , "Heart or club, say?" , "Comic" .)