Cheerfully casual (5-2-5)

I believe the answer is:

happy-go-lucky

(Other definitions for happy-go-lucky that I've seen before include "Cheerfully unconcerned about the future" , "Without a care in the world" , "Insouciant" , "Cheerfully irresponsible" , "Easy-going" .)

I've seen this clue in The Mirror.

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.