That’s no lady who prepared so carelessly! (3,3,3)

I believe the answer is:

any old how

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'carelessly' is the definition.
I don't know anything about this answer so I cannot judge whether this works.

'that's no lady who prepared' is the wordplay.
'no lady who' anagrams to 'ANY OLD HOW'.
Though, I'm not sure how the anagram is indicated.

'so' acts as a link.

Can you help me to learn more?

(Other definitions for any old how that I've seen before include "disorderly" , "casually" , "Without special care" .)

I've seen this clue in The Times.

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