Appetiser is able to simulate (6)
I believe the answer is:
canape
'appetiser' is the definition.
(canapes are served as appetisers)
'able to simulate' is the wordplay.
'able' becomes 'can'.
'to simulate' becomes 'ape' (I've seen this before).
'can'+'ape'='CANAPE'
'is' acts as a link.
(Other definitions for canape that I've seen before include "cocktail treat" , "Savoury appetiser, often accompanied by Champagne" , "Savoury mouthful" , "Cocktail delicacy" , "Hors d'oeuvre" .)