### Clue: Large pet? Pet belonging to mum? (7)
### Answer: MASTIFF 
 ### Explanation: MA'S(possessive pronoun of "ma";belonging to mother) TIFF(a disagreement, especially between friends or lovers, which could, I guess, cause or be caused by a pet;a fit of sulking).
Defn: …, of the canine variety.**
The largest of the large?