Brood left in southern country (4)
I believe the answer is:
sulk
'brood' is the definition.
('sulk' can be a synonym of 'brood')
'left in southern country' is the wordplay.
'left' becomes 'l' (common abbreviation).
'in' means one lot of letters goes inside another.
'southern' becomes 's' (abbreviation).
'country' becomes 'uk' (UK is an example**).
's'+'uk'='suk'
'l' placed within 'suk' is 'SULK'.
(Other definitions for sulk that I've seen before include "Be bad-tempered and sullen" , "Be sullen and ill-tempered" , "Mood of sullen aloofness" , "Pout" , "Crime involving fire" .)