Teacher's waffle endless (5)
I believe the answer is:
rabbi
'teacher's' is the definition.
(Jewish teacher)
'waffle endless' is the wordplay.
'waffle' becomes 'rabbit' (both can mean to talk excessively).
'endless' means to remove the last letter.
'rabbit' with its last letter removed is 'RABBI'.
(Other definitions for rabbi that I've seen before include "Religious leader of Jewish congregation" , "Legal expert" , "Jewish law expounder" , "A Jewish clergyman" , "Sacks, for example" .)