A maths formula which leaves one breathless (6)

I believe the answer is:

asthma

'which leaves one breathless' is the definition.
(I've seen this before)

'a maths formula' is the wordplay.
'formula' is an anagram indicator (the letters are the ingredients or formula).
'maths' anagrammed gives 'sthma'.
'a'+'sthma'='ASTHMA'

(Other definitions for asthma that I've seen before include "Mat has difficult breathing" , "Breathing illness" , "Respiratory disease" , "which leaves one breathless" , "Physical disorder" .)

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

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