Band is ultimately rubbish (6)
I believe the answer is:
stripe
'band' is the definition.
(I know that band can be written as stripe)
'is ultimately rubbish' is the wordplay.
'ultimately' indicates one should take the final letters.
'rubbish' becomes 'tripe' (both can mean nonsense).
The final letter of 'is' is 's'.
's'+'tripe'='STRIPE'
(Other definitions for stripe that I've seen before include "Band of colour - 3 of rank" , "Sleeve badge showing military rank" , "Broad band" , "Sign of a soldier's rank" , "24 across (anag)" .)