Tear fastener (3)
I believe the answer is:
zip
I believe this is a double definition.
'tear' is the first definition.
(I know that tear can be written as zip)
'fastener' is the second definition.
(I know that zip is a type of fastener)
(Other definitions for zip that I've seen before include "Toothed fastener" , "Locking device with two toothed edges and a sliding tab" , "Sound of bullet passing" , "Energy or clothes fastener" , "Fastening device" .)