How do I solve 21 across in Times Cryptic 29566?

Question

Accepted Answer

21 across reads "Spiffing idea in puff?" (6 letters); the answer is WHEEZE. 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.

Spiffing idea in puff? (6)

21A — Spiffing idea in puff? (6) — WHEEZE