Flipping huge country market (4)
I believe the answer is:
souk
'market' is the definition.
(souk is a kind of market)
'flipping huge country' is the wordplay.
'flipping' shows that the letters should be reversed in order.
'huge' becomes 'os' (abbreviation for outsize).
'country' becomes 'uk' (United Kingdom).
'os' backwards is 'so'.
'so'+'uk'='SOUK'
(Other definitions for souk that I've seen before include "Marketplace in Muslim countries" , "Arab open-air market" , "Eastern market" , "Arab bazaar" , "Arab marketplace" .)