Lacuna, hiatus (3)
I believe the answer is:
gap
I believe this clue is a double definition.
'lacuna' is the first definition.
(I've seen this in another clue)
'hiatus' is the second definition.
(I've seen this before)
(Other definitions for gap that I've seen before include "Narrow opening" , "Disparity" , "Cleft" , "Interval, space" , "Empty space between things" .)