Homer's epic journey (7)
I believe the answer is:
odyssey
'homer's epic journey' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for odyssey that I've seen before include "Epic poem - epic voyage" , "Heroic journey" , "'Long eventful journey, such as that of Ulysses (7)'" , "A long adventurous journey - see Homer" , "Homerian epic" .)