Priest leaving church leader a true tale translated for Alfred, Lord Tennyson once (4,8)
I believe the answer is:
poet laureate
'alfred lord tennyson once' is the definition.
I can't explain the rest of the clue.
(Other definitions for poet laureate that I've seen before include "Official versifier" , "Court versifier" , "Wordsworth, for instance" , "such as Tennyson" , "Official verse writer" .)