Trouble with day working? Sticking at it, no matter what (10)

I believe the answer is:

obdurately

'sticking at it no matter what' is the definition.
(obdurate means stubborn or obstinate)

'trouble with day working?' is the wordplay.
'with' means one lot of letters go next to another.
'working?' indicates anagramming the letters.
'trouble'+'day'='troubleday'
'troubleday' anagrammed gives 'OBDURATELY'.

I've seen this clue in The Telegraph.

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