British equipment in prison (4)
I believe the answer is:
brig
'prison' is the definition.
(I've seen this before)
'british equipment' is the wordplay.
'british' becomes 'b' (abbreviation e.g. in BBC).
'equipment' becomes 'rig' (rig is a kind of equipment).
'b'+'rig'='BRIG'
'in' is the link.
(Other definitions for brig that I've seen before include "Ship; a ship's jail" , "Sailing vessel or lock-up on board" , "Two-masted square-rigger" , "Sailing-vessel" , "Two-masted square-rigged vessel" .)