Impartial test desired in crashes (13)
I believe the answer is:
disinterested
'impartial' is the definition.
(similar in meaning)
'test desired in crashes' is the wordplay.
'crashes' is an anagram indicator.
'test'+'desired'+'in'='testdesiredin'
'testdesiredin' is an anagram of 'DISINTERESTED'.
(Other definitions for disinterested that I've seen before include "Not expecting any profit" , "Impartial" , "Objective - uninvolved" , "Feeling no concern" , "Unbiased" .)