Get away from where the guns are pointing, Jack (3)
I believe the answer is:
'jack' is the definition.
(both are informal terms for sailor)
'get away from where the guns are pointing' is the wordplay.
'away from' is a deletion indicator.
'where the guns are pointing' becomes 'target' (guns might be pointed at a target).
'target' with 'get' taken out is 'TAR'.
(Other definitions for tar that I've seen before include "Viscous liquid; sailor" , "Hearty" , "Road surfacing or old sailor" , "Sailor; road surface" , "Naval man" .)