Yawns (5)
I believe the answer is:
'yawns' is the definition.
('gape' can be a synonym of 'yawn')
This is the entire clue.
(Other definitions for gapes that I've seen before include "Yawns" , "Looks on with open mouth" , "Stares at with mouth wide open" , "goggles" , "seems very surprised" .)