The weird loony wasted away (8)
I believe the answer is:
withered
'wasted away' is the definition.
(thesaurus)
'the weird loony' is the wordplay.
'loony' is an anagram indicator.
'the'+'weird'='theweird'
'theweird' is an anagram of 'WITHERED'.
(Other definitions for withered that I've seen before include "declined" , "like Keats's sedge?" , "Lost freshness and dried up" , "Having lost all moisture, vegetation, say" , "Wrinkled by shrinkage from age" .)