Twain being spoken of, also (3)
I believe the answer is:
too
'also' is the definition.
(I know that also can be written as too)
'twain being spoken of' is the wordplay.
I cannot really understand how this works, but
'of' could be 'o' and 'o' is located in the answer.
The remaining letters 'to' 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 too that I've seen before include "To a greater than desirable extent" , "Furthermore" , "As well; in addition" , "Likewise" , "As well, also" .)