Join outfit surrounding north (4)
I believe the answer is:
knit
'join' is the definition.
(I know that knit is a more specific form of the action join)
'outfit surrounding north' is the wordplay.
'outfit' becomes 'kit' (synonyms).
'surrounding' is an insertion indicator.
'north' becomes 'N' (abbreviation).
'kit' going around 'n' is 'KNIT'.
(Other definitions for knit that I've seen before include "Use needles to make clothes" , "(Bone) heal; contract (brows)" , "Work with wool and needles" , "Make woollen garments" , "Unite together" .)