Crossword Genius

With Sinuous Sue on toadstool, boy endlessly agog is very shy (7,3,3,2,1,5)

Ross

I believe the answer is:

wouldnt say boo to a goose

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'endlessly agog is very shy' is the definition.
I know nothing about this answer so I can't tell whether this works.

'with sinuous sue on toadstool boy' is the wordplay.
I cannot really understand how this works, but
'with' could be 'w' (short for with) and 'w' is found within the answer.
'on' could be 'to' and 'to' is found in the answer.
an anagram of 'boy' is 'ybo' which is located in the answer.
This explanation may well be incorrect...

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