Forced open (6)
I believe the answer is:
prised
'forced open' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for prised that I've seen before include "Levered open by spider" , "Forced open with leverage" , "Levered (forcibly)" , "Forced open with a lever" , "Jemmied, levered" .)