Endless roulade, initially eaten in a frenzy, then left (7)
I believe the answer is:
eternal
'endless' is the definition.
(I know that endless can be written as eternal)
'roulade initially eaten in a frenzy then left' is the wordplay.
'initially' says to take the initial letters.
'in a frenzy' indicates an anagram.
'then' is a charade indicator (letters next to each other).
'left' becomes 'l' (common abbreviation).
The initial letter of 'roulade' is 'r'.
'r'+'eaten'='reaten'
'reaten' anagrammed gives 'eterna'.
'eterna'+'l'='ETERNAL'
(Other definitions for eternal that I've seen before include "Never failing" , "abiding" , "always to be remembered" , "Valid for all time" , "'Lasting forever, unending (7)'" .)