Group wanting mature dress (7)
I believe the answer is:
bandage
'dress' is the definition.
(I know that bandage is a more specific form of the action dress)
'group wanting mature' is the wordplay.
'group' becomes 'band' (band can mean a group of people).
'wanting' is a charade indicator (letters next to each other).
'mature' becomes 'age' (synonyms).
'band'+'age'='BANDAGE'
(Other definitions for bandage that I've seen before include "medical cover" , "Surgical dressing" , "Wrapping for wound" , "Wound dressing" , "Bind (a wound)" .)