Displaying frivolity in speech about quartz, for example (6)
I believe the answer is:
silica
'example' is the definition.
Although both the answer and definition are singular nouns, I can't see how one could define the other.
'displaying frivolity in speech about quartz' is the wordplay.
I cannot quite see how this works, but
'about' could be 'ca' (abbreviation for 'circa') and 'ca' is located in the answer.
This may be the basis of clue (or it may be nonsense).
'for' acts as a link.
Can you help me to learn more?
(Other definitions for silica that I've seen before include "Constituent of sandstone and quartz" , "Hard colourless compound from rocks" , "Eg, quartz" , "Glassy substance in quartz and sand" , "Main constituent of sandstone" .)