Northerner drunk outside clubs (4)
I believe the answer is:
scot
'northerner' is the definition.
(someone from Scotland)
'drunk outside clubs' is the wordplay.
'drunk' becomes 'sot' (both can mean someone who drinks too much).
'outside' means one lot of letters goes inside another.
'clubs' becomes 'c' (abbreviation used in card games such as bridge).
'sot' enclosing 'c' is 'SCOT'.
(Other definitions for scot that I've seen before include "Northern member of UK" , "One from north of the border" , "Aberdonian possibly" , "Glaswegian perhaps" , "Stevenson was one" .)