Critters upset plate with last of oats (7)
I believe the answer is:
animals
'critters' is the definition.
I can't tell whether this definition defines the answer.
'upset plate with last of oats' is the wordplay.
'upset' says the letters should be written in reverse.
'plate' becomes 'lamina' (anatomical term for a plate or layer).
'with' says to put letters next to each other.
'last of' indicates one should take the final letters.
The last letter of 'oats' is 's'.
'lamina' backwards is 'animal'.
'animal'+'s'='ANIMALS'
Can you help me to learn more?
(Other definitions for animals that I've seen before include "Beasts, creatures" , "Wild beasts" , "Living organisms characterised by voluntary movement" , "pets maybe" , "Beastly types" .)