Odd somehow to find a jewel on this car (6)
I believe the answer is:
dodgem
'this car' is the definition.
(I've seen this before)
'odd somehow to find a jewel' is the wordplay.
'somehow' is an anagram indicator.
'to find' means one lot of letters go next to another.
'a jewel' becomes 'gem' ('gem' can be a synonym of 'jewel').
'odd' anagrammed gives 'dod'.
'dod'+'gem'='DODGEM'
'on' is the link.
(Other definitions for dodgem that I've seen before include "ride - with 14a" , "Bumper car" , "Fairground amusement vehicle" , "Car used in fairground" , "Electric car" .)