Speaker prepared to roar (6)
I believe the answer is:
orator
'speaker' is the definition.
(I know that orator is a type of speaker)
'prepared to roar' is the wordplay.
'prepared' indicates an anagram.
'to'+'roar'='toroar'
'toroar' with letters rearranged gives 'ORATOR'.
(Other definitions for orator that I've seen before include "Skilled public speaker" , "Eloquent public speaker" , "One who holds forth" , "A gifted public speaker" , "A Rhetorical talker or speech-maker" .)