Abominable snowmen (5)
I believe the answer is:
yetis
'abominable snowmen' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for yetis that I've seen before include "Beasts that aren't real" , "Abominable snowmen" , "Mountain monsters" , "More than one mythic creature" , "Mythical creatures" .)