Similar people offered his brat a novel (5,2,1,7)
I believe the answer is:
birds of a feather
'similar people' is the definition.
I know nothing about this answer so I cannot judge whether it can be defined by this definition.
'offered his brat a novel' is the wordplay.
'novel' indicates an anagram (letters in a new or novel order).
'offered'+'his'+'brat'+'a'='offeredhisbrata'
'offeredhisbrata' is an anagram of 'BIRDS OF A FEATHER'.
Can you help me to learn more?
(Other definitions for birds of a feather that I've seen before include "Like people" , "sitcom" , "A kind" , "people of similar character" , "like-minded people" .)