Opens mouth, but runs out of fruit (5)
I believe the answer is:
gapes
'opens mouth' is the definition.
I don't understand how the remainder of the clue works.
(Other definitions for gapes that I've seen before include "Looks amazedly into pages" , "Opens mouth wide in surprise" , "Stares at with mouth wide open" , "Looks on with open mouth" , "Yawns" .)