Gallant resistance holding up a vehicle somehow (9)
I believe the answer is:
chevalier
'gallant' is the definition.
(thesaurus)
'resistance holding up a vehicle somehow' is the wordplay.
'resistance' becomes 'r' (electronics abbreviation).
'holding up' says to put letters next to each other (some letters go underneath or hold up others).
'somehow' indicates an anagram.
'a'+'vehicle'='avehicle'
'avehicle' is an anagram of 'chevalie'.
'r' after 'chevalie' is 'CHEVALIER'.
(Other definitions for chevalier that I've seen before include "Gallant French" , "Old (French) "knight"" , "courteous type" , "young Charlie?" , "Each viler than the strange knight" .)