Identification of disease in dogs is a diversion (9)
I believe the answer is:
diagnosis
'identification of disease' is the definition.
(I've seen this before)
'in dogs is a diversion' is the wordplay.
'diversion' indicates an anagram.
'in'+'dogs'+'is'+'a'='indogsisa'
'indogsisa' with letters rearranged gives 'DIAGNOSIS'.
(Other definitions for diagnosis that I've seen before include "doctor's opinion" , "Identification of a problem from its symptoms" , "Identification of disease" , "Doctor's verdict" , "medical opinion" .)