A groovy little diamond, perhaps (6)
I believe the answer is:
stylus
'a groovy little diamond' is the definition.
The definition and answer can be both man-made objects as well as being singular nouns.
Maybe there's a link between them I don't understand?
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for stylus that I've seen before include "LP tracker" , "LP tracking point" , "One going on record" , "Pointed device on a record player" , "Device attached to the cartridge of a record player" .)