Some mourn a humble Hebrew prophet (5)
I believe the answer is:
nahum
'hebrew prophet' is the definition.
(I've seen this in another clue)
'some mourn a humble' is the wordplay.
'some' says the answer is hidden in the clue (some of the parts of the word are used).
'NAHUM' is hidden within 'mourn a humble'.
(Other definitions for nahum that I've seen before include "Minor prophet" , "Hebrew prophet - Biblical book" , "OT book and prophet who foretold the fall of Nineveh" , "Old Hebrew prophet" , "Prophet's book" .)