How do I solve 10 across in Daily Telegraph Cryptic 31273?

Question

Accepted Answer

10 across reads "Rubbish fossil fuels recommendation?" (7 letters); the answer is USELESS. 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.

Rubbish fossil fuels recommendation? (7)

10A — Rubbish fossil fuels recommendation? (7) — USELESS