Understood the Speaker’s outburst (4)
I believe the answer is:
seen
'understood' is the definition.
(I've seen this in another clue)
'speaker's outburst' is the wordplay.
'speaker's' indicates a 'sounds like' (homophone) clue.
'outburst' becomes 'scene' (as in making a scene in public).
'scene' is a homophone of 'SEEN'.
'the' acts as a link.
(Other definitions for seen that I've seen before include "Viewed" , "Espied" , "watched" , "Met - understood" , "Sighted" .)