Fatigue as heinous tax rejigged (10)

I believe the answer is:

exhaustion

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

'fatigue' is the definition.
(exhaustion is a kind of fatigue)

'heinous tax rejigged' is the wordplay.
'heinous tax' can be anagrammed to 'EXHAUSTION'.
However, I am unsure how the anagram is indicated.

'as' acts as a link.

Can you help me to learn more?

(Another definition for exhaustion that I've seen is " fatigue".)

I've seen this clue in The Guardian.

Want a hint initially instead of a full solution? Install my app