At bargain time around Birkenhead, this is still expensive (5)
I believe the answer is:
sable
'at' is the definition.
The definition and answer can be both substances as well as being singular nouns.
Maybe you can see a link between them that I can't see?
'bargain time around birkenhead this is still expensive' is the wordplay.
I cannot really understand how this works, but
'birkenhead' could be 'b' (head letter of 'birken') and 'b' is present in the answer.
'bargain time' could be 'sale' (I've seen this in another clue) and 'sale' is found within the remaining letters.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for sable that I've seen before include "Type of fur" , "Dark brown - black" , "Antelope, fur" , "Dark brown fur of the marten" , "Fur from member of weasel family" .)