Religious leader could give endless talk (5)
I believe the answer is:
rabbi
'religious leader' is the definition.
(Jewish religious leader)
'endless talk' is the wordplay.
'endless' means to remove the last letter.
'talk' becomes 'rabbit' (rabbit can informally mean to talk).
'rabbit' with its final letter taken away is 'RABBI'.
'could give' acts as a link.
(Other definitions for rabbi that I've seen before include "Legal expert" , "Leader of worshippers" , "Minister of a synagogue" , "Religious leader of Jewish congregation" , "Teacher of Jewish law" .)