Doctor near turning expert (7)
I believe the answer is:
veteran
'expert' is the definition.
(veteran is a kind of expert)
'doctor near turning' is the wordplay.
'doctor' becomes 'vet' (vet is a kind of doctor).
'turning' indicates anagramming the letters.
'near' with letters rearranged gives 'eran'.
'vet'+'eran'='VETERAN'
(Other definitions for veteran that I've seen before include "Describing cars built before 1919, especially before 1905" , "Old soldier's" , "Person with long experience, as in American army" , "Warhorse" , "Past master" .)