Car valuation oddly ignored (4)
I believe the answer is:
auto
'car' is the definition.
('auto' can be a synonym of 'car')
'valuation oddly ignored' is the wordplay.
'oddly ignored' means one should take alternating letters.
The alternating letters of 'valuation' are 'AUTO'.
(Other definitions for auto that I've seen before include "Prefix to denote self or same" , "Car (American)" , "Car, in short" , "Car (mostly US)" , "Lincoln?" .)