It's a strange man outside with a dog (8)
I believe the answer is:
alsatian
'a dog' is the definition.
(alsatian is a kind of dog)
'it's a strange man outside' is the wordplay.
'strange' indicates an anagram.
'man' becomes 'alan' ().
'outside' indicates putting letters inside (some letters go outside others).
'its'+'a'='itsa'
'itsa' is an anagram of 'sati'.
'sati' inserted inside 'alan' is 'ALSATIAN'.
'with' is the link.
(Other definitions for alsatian that I've seen before include "Large dog and someone from northern France" , "Dog (from French border region?)" , "Old Frenchman" , "Large canine, may be police dog" , "Strong dog known as German Shepherd" .)