Brislings, fishes (6)
I believe the answer is:
sprats
I believe this clue is a double definition.
'brislings' is the first definition.
('sprat' can be a synonym of 'brisling')
'fishes' is the second definition.
(sprat is a kind of fish)
(Other definitions for sprats that I've seen before include "Small fish, set to catch whales" , "Small fish like sardines" , "Couple fussy about meat" , "Small fish used to catch larger ones" , "Small fishes used to catch larger ones" .)