Crossword Clue:

something added as a decoration

AnswerCrossword Clue
ONLAYDecoration added so as to be in relief.
ICESomething often added to a carbonated beverage
THREWINAdded as a bonus
APPENDEDAdded as a supplement
STIRREDINAdded, as to a recipe
EXTENDERSubstance added as a diluent.
EDGEDINAdded slyly, as a comment
COOPTEDAdded, as a fellow member
STIRREDAdded (in), as per a recipe
CUEDINAdded music to, as in a play