Impudent talk about vegetable and fish (8)
I believe the answer is:
Here is my best explanation:
'fish' is the definition.
(pilchard is a kind of fish)
'impudent talk about vegetable' is the subsidiary indication.
'impudent talk' becomes 'lip' (informal term for impolite remarks).
'about' shows that the letters should be reversed in order.
'vegetable' becomes 'chard' (chard is a kind of vegetable).
'lip' reversed gives 'pil'.
'and' is the link.
(Other definitions for pilchard that I've seen before include "'Small fatty fish, usually canned (8)'", "Small marine food fish", "Small sea fish related to the herring", "Food fish", "Small fatty fish, usually tinned", "Edible herring relative", "Fish of herring family", "Item of seafood", "Marine food fish" and "item".)