Doctor hunting loner ultimately (2,3,4,3)
I believe the answer is:
in the long run
'ultimately' is the definition.
(thesaurus)
'doctor hunting loner' is the wordplay.
'doctor' is an anagram indicator.
'hunting'+'loner'='huntingloner'
'huntingloner' with letters rearranged gives 'IN THE LONG RUN'.
(Other definitions for in the long run that I've seen before include "At the end of the day" , "some time later" , "Eventually" , "When all is said and done" , "qualified for a marathon?" .)