Feel sad with doctor having a terrible run (5)
I believe the answer is:
mourn
'feel sad' is the definition.
I can't judge whether this defines the answer.
'doctor having a terrible run' is the wordplay.
'doctor' becomes 'mo' (medical officer).
'having' means one lot of letters go next to another.
'a terrible' is an anagram indicator.
'run' anagrammed gives 'urn'.
'mo'+'urn'='MOURN'
'with' acts as a link.
Can you help me to learn more?
(Other definitions for mourn that I've seen before include "Grieve for a death" , "Regret (a loss)" , "Show sorrow at death" , "Be sad over loss" , "Keen" .)