Vermin (4)
'vermin' is the definition.
(rats are vermin)
This is the entire clue.
(Other definitions for rat that I've seen before include "one escaping doomed vessel?" , "Tell-tale" , "Rodent; traitor" , "Treacherous rodent" , "Cad" .)
(Other definitions for rats that I've seen before include "Damn" , "Mild oath - sewer residents" , "deserters" , "Snoopy's imprecation - vermin" , "(Hunts) rodents - expression of irritation" .)
'vermin' is the definition.
This is the entire clue.
(Other definitions for pest that I've seen before include "Plague" , "Disease with a high death rate" , "Nuisance; half a European capital" , "Aphis" , "Annoying thing" .)