Go berserk with anorak and jumper? (8)
I believe the answer is:
kangaroo
'jumper?' is the definition.
(I've seen this before)
'go berserk with anorak' is the wordplay.
'berserk with' indicates an anagram (I've seen this in other clues).
'go' mixed up with 'anorak' can make 'KANGAROO'.
'and' acts as a link.
(Other definitions for kangaroo that I've seen before include "Marsupial (both parts 4's friends)" , "one jumps" , "Bounding marsupial" , "Hopping marsupial" , "Pouched mammal" .)