Stay put (3,5)
I believe the answer is:
sit tight
'stay put' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for sit tight that I've seen before include "Remain firmly in place, take no action" , "Be too drunk to stand?" , "Wait and see!" , "Remain in sedentary posture, take no action" , "Go nowhere" .)