Hold forth in Windsor at Evensong (5)
I believe the answer is:
orate
'hold forth' is the definition.
(I've seen this before)
'in windsor at evensong' is the wordplay.
'in' indicates a hidden word.
'ORATE' can be found hidden inside 'windsor at evensong'.
(Other definitions for orate that I've seen before include "Speechify" , "Harangue" , "Make a formal speech" , "Speak in florid style" , "Speak publicly" .)