Crazy nightmare might be the case for Brazil (8)
'the case for brazil' is the definition.
(Brazil is a type of nut)
'crazy nightmare' is the wordplay.
'crazy' becomes 'nuts' (I've seen this before).
'nightmare' becomes 'hell'.
'nuts'+'hell'='NUTSHELL'
'might be' acts as a link.
(Other definitions for nutshell that I've seen before include "covering for seed" , "It holds the kernel (or summary?)" , "Part of Brazil" , "Hard fruit casing" , "Hard kernel covering" .)
'crazy' is the definition.
(thesaurus)
I can't explain the remainder of the clue.
(Other definitions for nuts that I've seen before include "Mad; seeds" , "Fruits; insane" , "Heads - fans - fruit" , "Bonkers" , "Nibbles" .)