Solo nude modelled astride car (10)
I believe the answer is:
unescorted
'solo' is the definition.
(thesaurus)
'nude modelled astride car' is the wordplay.
'modelled' is an anagram indicator (letters modelled or shaped).
'astride' indicates putting letters inside.
'car' becomes 'escort' (Ford Escort is a type of car).
'nude' anagrammed gives 'uned'.
'uned' enclosing 'escort' is 'UNESCORTED'.
(Other definitions for unescorted that I've seen before include "Without a guide" , "alone" , "Without company" .)