How do I solve 18 down in Times Cryptic 29569?

Question

Accepted Answer

18 down reads "Conventions area within airport?" (7 letters); the answer is CUSTOMS. 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.

Conventions area within airport? (7)

18D — Conventions area within airport? (7) — CUSTOMS