One northern team may be contained (6)
I believe the answer is:
inside
'contained' is the definition.
Both the answer and definition are adjectives. Perhaps there's a link between them I don't understand?
'one northern team' is the wordplay.
'one' becomes 'i' (Roman numeral).
'northern' becomes 'n' (abbreviation e.g. N. Ireland).
'team' becomes 'side' (both can mean a sports team).
'i'+'n'+'side'='INSIDE'
'may be' acts as a link.
Can you help me to learn more?
(Other definitions for inside that I've seen before include "Enid is (anag) - within" , "A sort of job" , "Inner surface" , "Behind bars (sl.)" , "Middle" .)