In no mood to enjoy life I reckon (5)

I believe the answer is:

irate

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

'in no mood to enjoy life' is the definition.
I can't tell whether this defines the answer.

'i reckon' is the wordplay.
'reckon' becomes 'rate' (I've seen this in other clues).
'i'+'rate'='IRATE'

Can you help me to learn more?

(Other definitions for irate that I've seen before include "Indignant, angry" , "raging" , "Extremely angry" , "Annoyed, exasperated" , "Ticked off" .)

I've seen this clue in The Globe and Mail.

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