Gloomy doctor put in a sensitive spot (6)
I believe the answer is:
sombre
'gloomy' is the definition.
(I've seen this before)
'doctor put in a sensitive spot' is the wordplay.
'doctor' becomes 'MB' (Bachelor of Medicine, Medicinae Baccalaureus).
'put in' indicates putting letters inside (back).
'a sensitive spot' becomes 'sore' (I've seen this in another clue).
'mb' going within 'sore' is 'SOMBRE'.
(Other definitions for sombre that I've seen before include "Lugubrious" , "Funereal" , "Dull, gloomy" , "Melancholy" , "Melancholic" .)