Boss breaks down and cries (4)
I believe the answer is:
sobs
'cries' is the definition.
(sobbing is a kind of crying)
'boss breaks down' is the wordplay.
'breaks down' is an anagram indicator.
'boss' with letters rearranged gives 'SOBS'.
'and' acts as a link.
(Other definitions for sobs that I've seen before include "Weeps noisily" , "Weeps heavily for boss" , "Cries noisily" , "Is unhappy" , "showing distress" .)