Porridge is put out to trap adult rodents (7,4)

'rodents' is the definition.
(prairie dog is a kind of rodent)

'porridge is put out to trap adult' is the wordplay.
'put out' is an anagram indicator.
'to trap' means one lot of letters goes inside another.
'adult' becomes 'a' (abbreviation).
'porridge'+'is'='porridgeis'
'porridgeis' is an anagram of 'pririedogs'.
'pririedogs' going around 'a' is 'PRAIRIE DOGS'.