Mineral used in ceramic art (4)
I believe the answer is:
mica
'mineral' is the definition.
(mica is a kind of mineral)
'in ceramic art' is the wordplay.
'in' indicates the answer is hidden within the clue.
'MICA' is hidden within 'ceramic art'.
'used' is the link.
(Other definitions for mica that I've seen before include "Flexible mineral found in igneous and metamorphic rocks" , "Shiny silicate mineral" , "Muscovite with perfect cleavage" , "Isinglass" , "Semitransparent insulating mineral" .)