Old priest among the Israelites (3)
I believe the answer is:
eli
'old priest' is the definition.
(Biblical character)
'among the israelites' is the wordplay.
'among' indicates a hidden word.
'ELI' is hidden within 'israelites'.
(Other definitions for eli that I've seen before include "Distort then untruth to get a Biblical character" , "Samuel's teacher (OT)" , "Old Testament high priest" , "Biblical high priest" , "Old Testament priest, the prophet Samuel's teacher" .)