"concert"

This is a reversal clue - look for indicators like 'back', 'returned', 'up' (in down clues), or 'west' (in across clues)

Reverse the letters of a word from the clue

Answer: UNISON | Definition: 'concert' | Wordplay: A reversal (‘to turn up’ in a down light) of NO SIN (‘only good’) plus U (‘uniform’).