Are to possibly speak (5)
I believe the answer is:
orate
'speak' is the definition.
(I know that orate is a more specific form of the action speak)
'are to possibly' is the wordplay.
'possibly' indicates an anagram.
'are'+'to'='areto'
'areto' with letters rearranged gives 'ORATE'.
(Other definitions for orate that I've seen before include "make speeches" , "Lecture" , "Talk pompously" , "Make a formal speech" , "Declaim or rant" .)