Poor characters lose the head and capture pest seen speechifying (6)
I believe the answer is:
orator
'poor characters lose the head and capture' is the definition.
I can't tell whether this defines the answer.
'pest seen speechifying' is the wordplay.
I cannot quite see how this works, but
'pest' could be 'rat' (rat can mean a nasty person) and 'rat' is located in the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for orator that I've seen before include "Eloquent public speaker" , "One addressing" , "An impressive public speaker" , "Eloquent type" , "Rhetorician" .)