Mountain gap (5)
'mountain gap' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for notch that I've seen before include "Make the cut" , "Indentation - step up" , "small score?" , "Indentation, nick" , "V-shaped nick" .)
(Other definitions for pass that I've seen before include "Amatory advance" , "Don't answer a question" , "asked for permission to enter" , "Get beyond" , "Exceed; leave behind" .)