Sweets in aspic, and yucky! (5)
I believe the answer is:
candy
'sweets' is the definition.
(I've seen this before)
'in aspic and yucky' is the wordplay.
'in' indicates a hidden word.
'CANDY' is hidden within 'aspic and yucky'.
(Other definitions for candy that I've seen before include "Crystallised sugar; US sweets" , "Sugary sweet" , "Girl's name (diminutive)" , "American confectionary" , "American sweets" .)