Nothing but clamour in Valhalla (4)
I believe the answer is:
odin
'valhalla' is the definition.
Although both the answer and definition are singular nouns, I cannot understand how one could define the other.
'nothing but clamour' is the wordplay.
I cannot really see how this works, but
'nothing' could be 'o' (O resembles 0) and 'o' is found in the answer.
'clamour' could be 'din' (I've seen this before) and 'din' is found within the answer.
No letters remain.
This explanation may well be incorrect...
'in' is the link.
Can you help me to learn more?
(Other definitions for odin that I've seen before include "Supreme god of Scandanavian myth" , "Legendary ruler" , "who's worshipped" , "King of Norse gods" , "Legendary Scandinavian" .)