Empty, thats obvious (5)
I believe the answer is:
clear
I believe this clue is a double definition.
'empty' is the first definition.
(I've seen this before)
'obvious' is the second definition.
(similar in meaning)
'thats' is the link.
(Other definitions for clear that I've seen before include "Transparent, easy to see through" , "Not obstructed" , "Jump over without contact" , "Leap over" , "Unobstructed" .)