Joke, wisecrack (3)
I believe the answer is:
gag
I believe this is a double definition.
'joke' is the first definition.
(a gag is a joke or witticism)
'wisecrack' is the second definition.
(I've seen this in another clue)
(Other definitions for gag that I've seen before include "Humorous anecdote or remark" , "Choke; joke" , "Stop someone telling" , "Retch at the joke?" , "that renders one speechless" .)