How do I solve 2 down in Daily Telegraph Cryptic 31244?

Question

Accepted Answer

2 down reads "Traitor taking harnesses off" (5,2,3,5 letters); the answer is SNAKE IN THE GRASS. 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.

Traitor taking harnesses off (5,2,3,5)

2D — Traitor taking harnesses off (5,2,3,5) — SNAKE IN THE GRASS