Open with a thin cut (4)
I believe the answer is:
slit
(Other definitions for slit that I've seen before include "Long narrow cut" , "Incision" , "Narrow straight cut or opening" , "Narrow aperture" , "Long narrow opening" .)
I believe the answer is:
slit
(Other definitions for slit that I've seen before include "Long narrow cut" , "Incision" , "Narrow straight cut or opening" , "Narrow aperture" , "Long narrow opening" .)