Shy doctor resumed scratching Charles's back (6)
I believe the answer is:
demure
'shy' is the definition.
(I've seen this in another clue)
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for demure that I've seen before include "Chaste" , "Coy, shy" , "Prim, coy" , "butter not melting in mouth?" , "Shy, prim" .)