How do I solve 27 across in Daily Telegraph Cryptic 31262?

Question

Accepted Answer

27 across reads "Farewell greatest hits album?" (3,3,4 letters); the answer is ALL THE BEST. It's a double-definition clue: two separate definitions of the same word sit side by side. No wordplay split and no indicators — both halves of the clue define the answer. The full step-by-step breakdown is on this page.

Farewell greatest hits album? (3,3,4)

27A — Farewell greatest hits album? (3,3,4) — ALL THE BEST