Silica, mixed with art, might be sarcastic (9)
I believe the answer is:
satirical
'sarcastic' is the definition.
(similar in meaning)
'silica mixed with art' is the wordplay.
'mixed with' is an anagram indicator.
'silica' anagrammed with 'art' can make 'SATIRICAL'.
'might be' is the link.
(Other definitions for satirical that I've seen before include "Ridiculing" , "scornful" , "Humorously critical" , "of burlesque" , "Exposing human folly to ridicule" .)