The beasts get cross when one staggers around! (4)
I believe the answer is:
oxen
'the beasts' is the definition.
(I have seen 'Beasts of burden ' mean 'oxen' so perhaps 'beasts' could also mean 'oxen')
'cross when one staggers around' is the wordplay.
'cross when' becomes 'x' (X is cross-shaped. I am not sure about the 'when' bit.).
'staggers' is an anagram indicator (I've seen 'staggering' mean this (letters stagger around)).
'around' means one lot of letters goes inside another.
'one' is an anagram of 'oen'.
'x' put within 'oen' is 'OXEN'.
'get' acts as a link.
Can you help me to learn more?
(Other definitions for oxen that I've seen before include "Bullocks" , "Draught animals" , "Doctored bulls" , "Heavy cattle" , "(E.g. draught) cattle" .)