Current content of mere banner (8)
I believe the answer is:
streamer
'banner' is the definition.
(both can mean a flag)
'current content of mere' is the wordplay.
'current' becomes 'stream' (synonyms).
'content of mere' becomes 'er' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'stream'+'er'='STREAMER'
Can you help me to learn more?
(Other definitions for streamer that I've seen before include "Long flag, often tapering" , "Arrest me carrying floating ribbon" , "Ribbon - bad cold?" , "awful cold?" , "that hangs about now?" .)