Introduction for endless eulogy, appalling (8)
I believe the answer is:
prologue
'introduction' is the definition.
(I know that prologue is a type of introduction)
'for endless eulogy appalling' is the wordplay.
'for' becomes 'pro' (as in being 'pro' something).
'endless' means to remove the last letter.
'appalling' indicates an anagram (an appalling spelling).
'eulogy' with its final letter removed is 'eulog'.
'eulog' anagrammed gives 'logue'.
'pro'+'logue'='PROLOGUE'
(Other definitions for prologue that I've seen before include "opening speech" , "Start to play" , "Foreword" , "Poor glue (anag.)" , "Introduction to a play or story" .)