Digital opponents so transfixed by doctor (6)
I believe the answer is:
thumbs
'digital opponents' is the definition.
Although both the answer and definition are plural nouns, I don't understand how they can define each other.
'so transfixed by doctor' is the wordplay.
'so' becomes 'thus' (synonyms).
'transfixed by' means one lot of letters goes inside another.
'doctor' becomes 'MB' (Bachelor of Medicine, Medicinae Baccalaureus).
'thus' enclosing 'mb' is 'THUMBS'.
Can you help me to learn more?
(Other definitions for thumbs that I've seen before include "Hitches a lift" , "To be all these is to be clumsy" , "Digits; requests (lift)" , "reads intensively" , "Short thick digits" .)