A doctor breaks into another dance (5)
I believe the answer is:
mambo
'dance' is the definition.
(I know that dance is a is a more specific form of the action of mambo)
'a doctor breaks into another' is the wordplay.
'a doctor' becomes 'MB' (Bachelor of Medicine).
'breaks into' indicates putting letters inside (inserted letters break into the word).
'another' becomes 'mao' (I can't explain this - if you can you should believe this answer much more).
'mb' placed into 'mao' is 'MAMBO'.
Can you help me to learn more?
(Other definitions for mambo that I've seen before include "voodoo priestess" , "Latin American dance of Haitian origin" , "voodoo woman" , "Dance derived from voodoo rituals" , "Quick Caribbean dance" .)