V-shaped indentation (5)
I believe the answer is:
notch
'v-shaped indentation' 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 "Incision on an edge" , "Point or degree in a scale" , "Cleft" , "Tallying incision" , "Make the cut" .)