Jab with a finger (4)
I believe the answer is:
poke
'jab with a finger' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for poke that I've seen before include "bag" , "Thrust forward; sack" , "Nudge; a bonnet" , "Probe with stick" , "Jab or prod" .)