Bit of bother with a dog? (4)
I believe the answer is:
spot
'bit' is the definition.
(thesaurus)
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for spot that I've seen before include "Sight - site" , "Notice; skin blemish" , "Espy; mark" , "Mark - position - perceive" , "Identify" .)