Hip backing band in Japan? I'm not sure this is metal (7)
I believe the answer is:
niobium
'this is metal' is the definition.
(metallic element)
'hip backing band in japan? i'm not sure' is the wordplay.
'hip' becomes 'in' (both can mean fashionable).
'backing' says the letters should be written in reverse.
'band in japan?' becomes 'obi' (type of Japanese belt).
'i'm not sure' becomes 'um' (expression of hesitation).
'in' written backwards gives 'ni'.
'ni'+'obi'+'um'='NIOBIUM'
(Other definitions for niobium that I've seen before include "Silver-grey metallic element" , "Superconductive element" , "Chemical element, Nb" , "Silvery-grey metal, Nb" , "Silver-grey metal, Nb" .)