Christopher's taking in a number of small pets
I believe the answer is:
kittens
'small pets' is the definition.
The answer and definition can be both animals as well as being plural nouns.
Perhaps they are linked in a way I don't understand?
'christopher's taking in a number' is the wordplay.
'christopher's' becomes 'Kit's' (short for Christopher).
'taking in' is an insertion indicator.
'a number' becomes 'ten' (ten is a number).
'kits' placed around 'ten' is 'KITTENS'.
'of' is the link.
Can you help me to learn more?
(Other definitions for kittens that I've seen before include "Feline young" , "Feline youngsters" , "Young rabbits" , "Have such pets" , "Young felines" .)