Wild nights aren't what they used to be (6)
I believe the answer is:
things
'aren't what they used to be' is the definition.
The definition suggests an adverb but the answer is not.
'wild nights' is the wordplay.
'wild' indicates an anagram.
'nights' is an anagram of 'THINGS'.
Can you help me to learn more?
(Other definitions for things that I've seen before include "Stuff" , "Items" , "Objects" .)