Culls second-rate composition, being completely indifferent (7,4,4)

I believe the answer is:

couldnt care less

I'm a little stuck... Click here to teach me more about this clue!

'completely indifferent' is the definition.
I can't judge whether this definition defines the answer.

'culls second-rate composition' is the wordplay.
'composition' indicates an anagram (letters arranged or composed in a different order).
'culls'+'second'+'rate'='cullssecondrate'
'cullssecondrate' anagrammed gives 'COULDN'T CARE LESS'.

'being' is the link.

Can you help me to learn more?

I've seen this clue in The Irish Times.

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.