Crossword Genius

Way back when? In the end, I couldn't care less (4)

Ross

I believe the answer is:

yawn

'i couldn't care less' is the definition.
(a yawn can be an expression of indifference)

'way back when? in the end' is the wordplay.
'back' is a reversal indicator.
'in the end' suggests the final letters.
The final letter of 'when' is 'n'.
'way' back-to-front is 'yaw'.
'yaw'+'n'='YAWN'

(Other definitions for yawn that I've seen before include "Show tiredness/boredom" , "Show one is tired or bored" , "Involuntary sign of tiredness or boredom" , "Boring event" , "Oscitate" .)

I've seen this clue in The Independent.
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