Word list fool set up in delight (8)
I believe the answer is:
glossary
'word list' is the definition.
(I've seen this before)
'fool set up in delight' is the wordplay.
'fool' becomes 'ass' (ass is a kind of fool).
'set up' says the letters should be written in reverse.
'in' is an insertion indicator.
'delight' becomes 'glory' (I've seen this before).
'ass' reversed gives 'ssa'.
'ssa' put inside 'glory' is 'GLOSSARY'.
(Other definitions for glossary that I've seen before include "List of words with meanings" , "Specialised dictionary" , "Explanatory list of words" , "List of terms text uses" , "set of explanations" .)