Peak southeast of Olympus (4)
I believe the answer is:
ossa
'peak southeast of olympus' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for ossa that I've seen before include "So as to turn to bones" , "Greek mountains" , "So as to become a Greek mountain" , "Legendary mountain" , "To heap Pelion on -- is to compound difficulties" .)