How do I solve 19 across in Times Cryptic 5220?

Question

Accepted Answer

19 across reads "Show how to go from tube to Barking?" (5-5 letters); the answer is POTTY-TRAIN. 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.

Show how to go from tube to Barking? (5-5)

19A — Show how to go from tube to Barking? (5-5) — POTTY-TRAIN