Grumpy during trial at the end of the day (5)

I believe the answer is:

testy

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'grumpy' is the definition.
(testy can mean irritable or annoyed)

'trial at the end of the day' is the wordplay.
'trial' becomes 'test' (synonyms).
'at the end of' suggests the final letters.
The final letter of 'day' is 'y'.
'test'+'y'='TESTY'

'during' is the link.
I am not very happy about this link. It may belong to another bit of the clue.

Can you help me to learn more?

(Other definitions for testy that I've seen before include "Short-tempered" , "Captious" , "Quick to anger" , "Easily annoyed" , "Cross" .)

I've seen this clue in The Irish Times.

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