Musicians taking a long time dressing (7)
I believe the answer is:
bandage
'dressing' is the definition.
(dressing for a wound)
'musicians taking a long time' is the wordplay.
'musicians' becomes 'band' (group of musicians).
'taking' means one lot of letters go next to another.
'a long time' becomes 'age' (an age is a period of time).
'band'+'age'='BANDAGE'
(Other definitions for bandage that I've seen before include "Material for wound or injury" , "Wound dressing" , "Wrap for a wound" , "Cloth to cover injuries" , "Surgical dressing" .)