Depart with a boast (6)
I believe the answer is:
avaunt
'depart with a boast' is the definition.
I can't judge whether this defines the answer.
'with a boast' is the wordplay.
'with' is a charade indicator (letters next to each other).
'boast' becomes 'vaunt' (synonyms).
'a' next to 'vaunt' is 'AVAUNT'.
Can you help me to learn more?
(Other definitions for avaunt that I've seen before include "Go away (arch.)" , "make tracks" , "Old word for be off" , "Shakespearian begone, move on" , ""Get away!"" .)