Was she Shaw's parasite? (7)

I believe the answer is:

candida

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

'parasite?' is the definition.
(I've seen this before)

'was she shaw's' is the wordplay.
I cannot quite see how this works, but
'she' could be 'candi' and 'candi' is present in the answer.
The remaining letters 'da' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...

Can you help me to learn more?

(Other definitions for candida that I've seen before include "GBS play" , "Fungus" , "by G.B. Shaw" , "Parasite" .)

I've seen this clue in The Telegraph.

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