Explosive mania shown by loch beast (6)
I believe the answer is:
animal
'beast' is the definition.
(a beast is an animal)
'explosive mania shown by loch' is the wordplay.
'explosive' indicates an anagram.
'shown by' is a charade indicator (letters next to each other).
'loch' becomes 'l'.
'mania' with letters rearranged gives 'anima'.
'anima'+'l'='ANIMAL'
(Other definitions for animal that I've seen before include "Circus performer, maybe" , "One sharing our kingdom" , "Any organism capable of voluntary movement" , "It shares the world with vegetable and mineral" , "Brutal, sensual" .)