Jab quietly with stick (4)
I believe the answer is:
prod
'jab' is the definition.
('prod' can be a synonym of 'jab')
'quietly with stick' is the wordplay.
'quietly' becomes 'p' (p for piano and quiet).
'with' means one lot of letters go next to another.
'stick' becomes 'rod' (I've seen this before).
'p'+'rod'='PROD'
(Other definitions for prod that I've seen before include "Remind (with elbow or stick?)" , "Spur or goad" , "Poke with forefinger, stimulate" , "Induce action (with stick etc?)" , "Provide stimulation" .)