Essentially outthink best advisors in dissertation (6)
I believe the answer is:
thesis
'dissertation' is the definition.
(synonyms)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for thesis that I've seen before include "Learned dissertation" , "Long research essay or treatise written for university degree" , "Dissertation - idea" , "Long dissertation written to obtain university degree" , "Student dissertation" .)