Inspiring figure to speak after switching sides (5)
I believe the answer is:
erato
'inspiring figure' is the definition.
(muse of poetry in Greek mythology)
'to speak after switching sides' is the wordplay.
I cannot really see how this works, but
'to' is present in the answer.
The remaining letters 'era' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
(Other definitions for erato that I've seen before include "Poetic Muse ; eighteen (anag.)" , "poetical inspiration" , "Who may have inspired poetry" , "inspiration for poetry" , "Muse of lyric love-poetry" .)