Finally create one model in bone and rubber (7)
I believe the answer is:
ebonite
'rubber' is the definition.
(I know that ebonite is a type of rubber)
'finally create one model in bone' is the wordplay.
'finally' says to take the final letters.
'one' becomes 'i' (Roman numeral).
'model' becomes 't' (Ford Model T car).
'in' indicates putting letters inside.
The last letter of 'create' is 'e'.
'i'+'t'='it'
'it' put inside 'bone' is 'bonite'.
'e'+'bonite'='EBONITE'
'and' acts as a link.
(Other definitions for ebonite that I've seen before include "Vulcanite" , "something rubbery" , "Rubbery material" , "Bee on it (anag.)" , "vulcanised rubber" .)