Thea’s in a mad rush! (5)

I believe the answer is:

haste

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'rush' is the definition.
('haste' can be a synonym of 'rush')

'thea's in a mad' is the wordplay.
'thea's' can be anagrammed to 'HASTE'.
However, I am not clear how this is indicated.

Can you help me to learn more?

(Other definitions for haste that I've seen before include "Rash speed" , "The more of it, the less speed sometimes" , "Over-eager speed" , "Excessive speed or urgency" , "Rapidity" .)

I've seen this clue in the Evening Standard.

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