Beastly article tots are upset about (5)
I believe the answer is:
stoat
'beastly article tots are upset about' is the definition.
I can't tell whether this defines the answer.
'article tots are upset about' is the wordplay.
'article' becomes 'a' (indefinite article).
'are upset' is a reversal indicator.
'about' means one lot of letters goes inside another.
'tots' in reverse letter order is 'stot'.
'a' placed inside 'stot' is 'STOAT'.
Can you help me to learn more?
(Other definitions for stoat that I've seen before include "Eating rabbit, he" , "Small carnivorous mammal of the weasel family" , "Ermine in summertime?" , "Weasel, ermine" , "Small carnivore" .)