Vocally opposed stronghold (4)
I believe the answer is:
fort
'stronghold' is the definition.
(I've seen this before)
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for fort that I've seen before include "Strategic position" , "Defensive building" , "US gold reserves are at - Knox" , "Keep" , "William in Scotland" .)