Beastly change of rule about the fifth of November (5)
I believe the answer is:
lemur
'beastly change' is the definition.
Although both the answer and definition are singular nouns, I can't see how one could define the other.
'of rule about the fifth of november' is the wordplay.
'of' indicates an anagram (the answer comes from or 'of' the letters).
'about' is an insertion indicator.
'the fifth of november' becomes 'm' (fifth letter of the word 'November').
'rule' anagrammed gives 'leur'.
'leur' placed around 'm' is 'LEMUR'.
Can you help me to learn more?
(Other definitions for lemur that I've seen before include "Tree-dwelling primate" , "Tree-living primate" , "Primate found only in Madagascar" , "Animal with foxy face and long furry tail" , "one in the bush?" .)