Gloomy doctor gets a listener (5)
I believe the answer is:
drear
'gloomy' is the definition.
(I know that gloomy can be written as drear)
'doctor gets a listener' is the wordplay.
'doctor' becomes 'dr' (abbreviation).
'gets' says to put letters next to each other.
'a listener' becomes 'ear' (body part which hears or listens).
'dr'+'ear'='DREAR'
(Other definitions for drear that I've seen before include "Dismal, dull" , "Depressingly dull" , "Dull, bleak, depressing" , "Poetic dull and uninteresting" , "gloomy in poem" .)