Stress free? Chin up, mate, could be very different (10)

I believe the answer is:

unemphatic

'stress free?' is the definition.
(emphatic means with stress)

'chin up mate could be very different' is the wordplay.
'could be very different' is an anagram indicator (a very different ordering of the letters).
'chin'+'up'+'mate'='chinupmate'
'chinupmate' is an anagram of 'UNEMPHATIC'.

I've seen this clue in The Independent.

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