Submissive doctor is endlessly ill... has some earache (6)
I believe the answer is:
docile
'submissive' is the definition.
(I've seen this before)
'doctor is endlessly ill has some earache' is the wordplay.
'doctor' becomes 'doc' (synonyms).
'is endlessly' means to remove the last letter.
'has' is a charade indicator (letters next to each other).
'some' indicates taking the first letters.
The initial letter of 'earache' is 'e'.
'ill' with its last letter taken away is 'il'.
'doc'+'il'+'e'='DOCILE'
(Other definitions for docile that I've seen before include "Gentle and pliant" , "Gentle and teachable" , "Quiet, willing to obey" , "Easily managed and trainable" , "Manageable" .)