Band from the south has re-formed (4)
I believe the answer is:
sash
'band' is the definition.
(sash is a kind of band)
'the south has reformed' is the wordplay.
'the south' becomes 's' ('S' can be a synonym of 'south').
'reformed' indicates anagramming the letters.
'has' with letters rearranged gives 'ash'.
's'+'ash'='SASH'
'from' is the link.
(Other definitions for sash that I've seen before include "Brown bread for waist or shoulder" , "Type of sliding window" , "Decorative band" , "seen hanging around Miss World?" , "Decorative belt" .)