Sport lustrous jewellery in the ear (12)
I believe the answer is:
orienteering
'sport' is the definition.
Both the definition and answer are singular nouns.
Maybe you can see a link between them that I can't see?
'lustrous jewellery in the ear' is the wordplay.
I cannot really understand how this works, but
'jewellery' could be 'ring' (ring is a kind of jewellery) and 'ring' is found in the answer.
'the' could be 't' (the is pronounced as a 't' sound in some dialects) and 't' is located in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Another definition for orienteering that I've seen is " Sport using map and compass".)