Banners Poles badly singe beforehand (7)
I believe the answer is:
ensigns
'banners' is the definition.
(I've seen this in another clue)
'poles badly singe beforehand' is the wordplay.
'poles' becomes 'NS' (north and south poles).
'badly' indicates an anagram (letters in the wrong order).
'beforehand' is a charade indicator (letters next to each other).
'singe' with letters rearranged gives 'ensig'.
'ns' after 'ensig' is 'ENSIGNS'.
(Other definitions for ensigns that I've seen before include "Flag" , "standards" , "US naval officers" , "hauled up on deck?" , "Old soldiers" .)