Disturbing Alan, it's a dog (8)
I believe the answer is:
alsatian
'dog' is the definition.
(I know that Alsatian is a type of dog)
'disturbing alan it's a' is the wordplay.
'disturbing' is an anagram indicator (I've seen this in other clues).
'alan'+'its'+'a'='alanitsa'
'alanitsa' anagrammed gives 'ALSATIAN'.
(Other definitions for alsatian that I've seen before include "Strong dog known as German Shepherd" , "Large dog and person from northern France" , "Large dog and someone from Alsace" , "Large dog and someone from northern France" , "Dog (from French border region?)" .)