How do I solve 27 across in Daily Telegraph Cryptic 31241?

Question

Accepted Answer

27 across reads "Antagonistic Iran tests explosive" (9 letters); the answer is RESISTANT. 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.

Antagonistic Iran tests explosive (9)

27A — Antagonistic Iran tests explosive (9) — RESISTANT