Notice location (4)
I believe the answer is:
spot
I believe this is a double definition.
'notice' is the first definition.
(spot can mean to notice or observe)
'location' is the second definition.
(spot is a kind of location)
(Other definitions for spot that I've seen before include "Fix" , "Observe - locality" , "Notice; sign of acne" , "Small mark; see" , "Place - zit" .)