Gloomy doctor having a bad year (6)
I believe the answer is:
dreary
'gloomy' is the definition.
(I know that gloomy can be written as dreary)
'doctor having a bad year' is the wordplay.
'doctor' becomes 'dr' (abbreviation).
'having' means one lot of letters go next to another.
'a bad' is an anagram indicator.
'year' is an anagram of 'eary'.
'dr'+'eary'='DREARY'
(Other definitions for dreary that I've seen before include "Banal" , "Bleak, depressing" , "Dismal, funeral" , "routine" , "Dismal, boring" .)