Beast rejected beer following fine (5)
I believe the answer is:
okapi
'beast' is the definition.
(type of animal)
'rejected beer following fine' is the wordplay.
'rejected' says the letters should be written backwards.
'beer' becomes 'IPA' (India pale ale).
'following' says to put letters next to each other.
'fine' becomes 'ok' (synonyms).
'ipa' back-to-front is 'api'.
'api' put after 'ok' is 'OKAPI'.
(Other definitions for okapi that I've seen before include "Native of Central Africa" , "browser" , "Hoofed mammal" , "Animal of central Africa" , "Beast related to giraffe" .)