Small, oily fish (5)
(Other definitions for sprat that I've seen before include "Parts (anag.)" , "Tiny fish" , "Small edible fish" , "Small fish (used to catch mackerel?)" , "Herring's smaller relative" .)
(Other definitions for pilchard that I've seen before include "'Small fatty fish, usually canned (8)'" , "Small fatty fish, usually tinned" , "Fish of herring family" , "Small marine food fish" , "Small sea fish related to the herring" .)