How do I solve 17 across in Daily Telegraph Cryptic 31254?

Question

Accepted Answer

17 across reads "Gaelic bar cryptically using symbols instead of numbers" (9 letters); the answer is ALGEBRAIC. It's an anagram clue: the answer is a rearrangement of letters supplied by the clue itself. Look for an indicator like 'mixed', 'broken', 'cooked', or 'wild', and find a phrase whose letters add up to the answer's length. The full step-by-step breakdown is on this page.

Gaelic bar cryptically using symbols instead of numbers (9)

17A — Gaelic bar cryptically using symbols instead of numbers (9) — ALGEBRAIC