How do I solve 20 across in Times Cryptic 29566?

Question

Accepted Answer

20 across reads "Well, how might one spread butter?" (8 letters); the answer is SMOOTHLY. 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.

Well, how might one spread butter? (8)

20A — Well, how might one spread butter? (8) — SMOOTHLY