Related Clues:

• Mongrel
• Such a mongrel rottweiler, perhaps, will not be good-tempered
• Mule, e.g
• Mate (two different species)
• Mix, as dogs
• Such a strain, irritable and about to get into bed
• Mule, say, angry about standing in bottom of river
• Eg cockapoo, grumpy about being confined to bed