Metal band RC allowed on Channel Islands (7)
I believe the answer is:
circlet
'metal band' is the definition.
(I've seen this before)
'rc allowed on channel islands' is the wordplay.
'allowed' becomes 'let' (to let is to allow or permit).
'on' says to put letters next to each other.
'channel islands' becomes 'CI'.
'rc'+'let'='rclet'
'rclet' put after 'ci' is 'CIRCLET'.
(Other definitions for circlet that I've seen before include "Diadem" , "Metal band" , "Ornamental headband" , "Small round shape" , "Little hoop" .)