Bagatelle (6)
I believe the answer is:
trifle
'bagatelle' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for trifle that I've seen before include "Filter (anag.)" , "A little thing for the pudding" , "Small amount; dessert" , "Insignificant item - dessert" , "A small portion" .)