How do I solve 15 down in Daily Telegraph Cryptic 31253?

Question

Accepted Answer

15 down reads "French dish, lost cause, failed" (9 letters); the answer is CASSOULET. It's an anagram clue: the answer is a rearrangement of letters supplied by the clue itself. Look for an indicator like 'mixed', 'broken', 'cooked', or 'wild', and find a phrase whose letters add up to the answer's length. The full step-by-step breakdown is on this page.

French dish, lost cause, failed (9)

15D — French dish, lost cause, failed (9) — CASSOULET