Some tyres may be serrated (8)
I believe the answer is:
retreads
'some tyres' is the definition.
(retread is a kind of tyre)
'may be serrated' is the wordplay.
'may be' indicates an anagram.
'serrated' anagrammed gives 'RETREADS'.
(Other definitions for retreads that I've seen before include "Serrated like remoulded tyres" , "Serrated like tyres restored for use" , "recovered tyres" , "They gain fresh employment" , "Arrested over resurfaced tyres" .)