How do I solve 4 down in Times Cryptic 29535?

Question

Accepted Answer

4 down reads "Settled up with a lad? Stop" (8 letters); the answer is DIAPASON. It's a reversal clue: the answer is a word read backwards. Look for indicators like 'back', 'returned', or — in a down clue — 'up' or 'lifted'. Find the source word and reverse it. The full step-by-step breakdown is on this page.

Settled up with a lad? Stop (8)

4D — Settled up with a lad? Stop (8) — DIAPASON