Left in charge? Run away! (4)
I believe the answer is:
flee
'run away' is the definition.
(to flee is to run away)
'left in charge?' is the wordplay.
'left' becomes 'l' (common abbreviation).
'in' is an insertion indicator.
'charge?' becomes 'fee' (fee is a kind of charge).
'l' put within 'fee' is 'FLEE'.
(Other definitions for flee that I've seen before include "Leave" , "Run quickly away" , "retreat" , "head for the hills" , "rush" .)