Doctor has a chap upset (6)
I believe the answer is:
shaken
'upset' is the definition.
(I've seen this in another clue)
'doctor has a chap' is the wordplay.
'doctor' indicates anagramming the letters.
'a chap' becomes 'ken' (man's name).
'has' with letters rearranged gives 'sha'.
'sha'+'ken'='SHAKEN'
(Other definitions for shaken that I've seen before include "Astonished; vibrated" , "not left undisturbed" , "Upset or agitated" , "James Bond liked his martinis this way, not stirred" , "Shocked; astonished" .)