The PM arose to change prevailing mood (10)

I believe the answer is:

atmosphere

'prevailing mood' is the definition.
(atmosphere can mean a mood or air)

'the pm arose to change' is the wordplay.
'to change' is an anagram indicator.
'the'+'pm'+'arose'='thepmarose'
'thepmarose' anagrammed gives 'ATMOSPHERE'.

(Other definitions for atmosphere that I've seen before include "Pervading tone or mood" , "Gas surrounding a planet" , "prevailing mood" , "blue?" , "character" .)

I've seen this clue in The Times and The Independent.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.