Assembled yellow plant for audience (8)
I believe the answer is:
mustered
'assembled' is the definition.
(muster means to gather)
'yellow plant for audience' is the wordplay.
'yellow plant' becomes 'mustard' (plant with yellow flowers).
'for audience' shows a homophone (sound like).
'mustard' is a homophone of 'MUSTERED'.
(Other definitions for mustered that I've seen before include "Assembled, gathered together - say troops" , "Marshalled" , "Caused to assemble" , "Brought together" .)