These are sure to be brisk for beer on board (5)
I believe the answer is:
sales
'these are sure to be brisk' is the definition.
The definition suggests an adverb but the answer is not.
'beer on board' is the wordplay.
'beer' becomes 'ale' (type of beer).
'on' is an insertion indicator.
'board' becomes 'ss' (I've seen this in other clues).
'ale' going within 'ss' is 'SALES'.
'for' is the link.
Can you help me to learn more?
(Other definitions for sales that I've seen before include "a feature of Boxing Day?" , "Periods of price reductions" , "Opportunities to sell" , "Occasions for buying at reduced prices" , "Periods when shops sell goods at discounted prices, bargain times" .)