Son making fun of ornamental stitching (8)
I believe the answer is:
smocking
'fun of ornamental stitching' is the definition.
Although both the answer and definition are singular nouns, I don't see how one could define the other.
'son' is the wordplay.
I cannot quite see how this works, but
'son' could be 's' (genealogical abbreviation for son) and 's' is located in the answer.
The remaining letters 'mocking' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
'making' is the link.
Can you help me to learn more?
(Other definitions for smocking that I've seen before include "fancy needlework" , "Embroidery" , "stitched dress decoration" .)