Mark’s dog? (4)
I believe the answer is:
spot
This clue could be a double definition.
'mark's' is the first definition.
(spotting is a kind of marking)
'dog?' is the second definition.
The definition and answer can be both man-made objects as well as being singular nouns.
Maybe they are linked in a way I don't understand?
Can you help me to learn more?
(Other definitions for spot that I've seen before include "moral flaw" , "make out" , "Notice; sign of acne" , "Detect" , "point on snooker table" .)