Band having an outing in the south-east (6)
I believe the answer is:
stripe
'band' is the definition.
(synonyms)
'an outing in the south-east' is the wordplay.
'an outing' becomes 'trip' (I've seen this in another clue).
'in the' is an insertion indicator.
'south east' becomes 'SE' (abbreviation).
'trip' placed within 'se' is 'STRIPE'.
'having' acts as a link.
(Other definitions for stripe that I've seen before include "Broad band" , "Braid showing military rank" , "Sleeve badge showing military rank" , "Band of colour - 3 of rank" , "Distinctive band" .)