Standard terms are being modified (8)
I believe the answer is:
streamer
'standard' is the definition.
(I know that streamer is a type of standard)
'terms are being modified' is the wordplay.
'being modified' is an anagram indicator.
'terms'+'are'='termsare'
'termsare' is an anagram of 'STREAMER'.
(Other definitions for streamer that I've seen before include "Arrest me carrying floating ribbon" , "Heavy cold" , "Item of bunting" , "Long flag or decoration" , "Bit of bunting" .)