Silicate economically produced in part (4)
I believe the answer is:
mica
'silicate' is the definition.
(I've seen this in another clue)
'economically produced in part' is the wordplay.
'in part' indicates a hidden word.
'MICA' can be found hidden inside 'economically produced'.
(Other definitions for mica that I've seen before include "Semitransparent insulating mineral" , "Transparent mineral" , "Shiny silicate mineral" , "Isinglass" , "Flexible mineral found in igneous and metamorphic rocks" .)