Hair treatment from Barber in Seville (5)
I believe the answer is:
rinse
'hair treatment' is the definition.
(I've seen this in another clue)
'from barber in seville' is the wordplay.
'from' indicates the answer is hidden within the clue.
'RINSE' is hidden in the letters of 'barber in seville'.
(Other definitions for rinse that I've seen before include "Swill out" , "Hair colourant" , "Flush" , "blue one on top?" , "Cleanse in water" .)