Test the weight of (4)
I believe the answer is:
heft
'test the weight of' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for heft that I've seen before include "Lift, carry; influence" , "Lift or hold something to assess its weight" , "Lift in order to heave, say an axe" , "Judge the weight" , "Lift (something heavy)" .)