How do I solve 23 down in Daily Telegraph Cryptic 31242?

Question

Accepted Answer

23 down reads "Wasted on the radio? That's indecent" (4 letters); the answer is BLUE. It's a homophone clue: the answer sounds like another word. Indicators like 'reportedly', 'we hear', or 'sounds like' point to a word that's pronounced similarly to the answer. The full step-by-step breakdown is on this page.

Wasted on the radio? That's indecent (4)

23D — Wasted on the radio? That's indecent (4) — BLUE