As ordered by doctor, a dance (5)
I believe the answer is:
samba
'dance' is the definition.
(Brazilian dance)
'as ordered by doctor a' is the wordplay.
'ordered' indicates anagramming the letters.
'by' means one lot of letters go next to another.
'doctor' becomes 'mb' (Bachelor of Medicine, Medicinae Baccalaureus).
'as' is an anagram of 'sa'.
'sa'+'mb'+'a'='SAMBA'
(Other definitions for samba that I've seen before include "Dance, originally from Brazil" , "Latin dance" , "South American dance" , "This ambassador's > brisk steps" , "Dance music" .)