Gaps, apertures (5)
I believe the answer is:
holes
I believe this clue is a double definition.
'gaps' is the first definition.
(I know this)
'apertures' is the second definition.
(I've seen this in another clue)
(Other definitions for holes that I've seen before include "Cavities" , "Apertures" , "Empty spaces" , "Openings" , "Scrapes" .)