Violent robbery (4)
I believe the answer is:
blag
'violent robbery' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for blag that I've seen before include "Obtain by wheedling - robbery" , "Violent robbery - lying to get something" , "Lie to get something" , "Use clever talk to obtain something" , "Somehow obtain" .)