Buzzword for one thing that bosses and workers all are (5)
I believe the answer is:
human
'thing that bosses and workers all are' is the definition.
Although both the answer and definition are singular nouns, I can't understand how they can define each other.
'buzzword for one' is the wordplay.
'buzzword for' becomes 'hum' (I can't explain this - if you can you should believe this answer much more).
'one' becomes 'an' (I've seen this in other clues).
'hum'+'an'='HUMAN'
(Other definitions for human that I've seen before include "likely to err?" , "Not divine, animal or mechanical" , "Mortal; compassionate" , "Relating to a person" , "Genial, kind" .)