Dessert: it’s insignificant (6)
I believe the answer is:
trifle
I believe this clue is a double definition.
'dessert' is the first definition.
(trifle is a kind of dessert)
'it's insignificant' is the second definition.
(a trifle is something insignificant or trivial)
(Other definitions for trifle that I've seen before include "A little thing for the pudding" , "Insignificant item - dessert" , "Touch" , "Small amount; dish" , "Pudding - trinket" .)