Drop the rubbish and say your piece! (5)
I believe the answer is:
shoot
'drop' is the definition.
(thesaurus)
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for shoot that I've seen before include "Kill; part of plant" , "big game expedition?" , "Make a film" , "Say what you have to say" , "Fire (a gun)" .)