Ex-boozers acquiring unknown pub to host market (6)
I believe the answer is:
bazaar
'market' is the definition.
(bazaar is a kind of market)
'ex-boozers acquiring unknown pub to host' is the wordplay.
'ex boozers' becomes 'AA' (Alcoholics Anonymous).
'acquiring' means one lot of letters goes inside another.
'unknown' becomes 'z' (algebra).
'pub' becomes 'bar' (both are drinking establishments).
'to host' indicates putting letters inside (inserted letters are hosted or welcomed).
'aa' going around 'z' is 'aza'.
'aza' inserted within 'bar' is 'BAZAAR'.
(Other definitions for bazaar that I've seen before include "Group of shops or stalls, from the Orient" , "Group of stalls in oriental country" , "Fete" , "Middle East market - fundraising event" , "Fair" .)