Norwegian sprat is eaten by British fish (8)
I believe the answer is:
brisling
'norwegian sprat' is the definition.
(sprat produced in Norway)
'is eaten by british fish' is the wordplay.
'eaten by' is an insertion indicator (inserted letters get eaten).
'british' becomes 'br' (abbreviation for British).
'fish' becomes 'ling' (ling is a kind of fish).
'br'+'ling'='brling'
'is' inserted within 'brling' is 'BRISLING'.
(Other definitions for brisling that I've seen before include "Sprat sold in a can" , "Swimmer" , "Norwegian fish" , "Small fish of the herring family" .)