Eager longing to tear up t-shirt (6)

I believe the answer is:

thirst

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

'eager longing to tear' is the definition.
I can't tell whether this defines the answer.

'up t-shirt' is the wordplay.
'up' indicates an anagram (letters get chucked up).
't'+'shirt'='tshirt'
'tshirt' with letters rearranged gives 'THIRST'.

Can you help me to learn more?

(Other definitions for thirst that I've seen before include "Strong desire from dehydration?" , "Physiological need to drink" , "Long" , "Quaff to slake it" , "drought" .)

I've seen this clue in The Irish Times.

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