New course held by Rolls-Royce after parking sign (9)
I believe the answer is:
precursor
'sign' is the definition.
(precursor is a kind of sign)
'new course held by rolls-royce after parking' is the wordplay.
'new' is an anagram indicator.
'held by' indicates putting letters inside.
'rolls royce' becomes 'rr' (short for Rolls Royce).
'after' is a charade indicator (letters next to each other).
'parking' becomes 'p' (abbreviation on road signs).
'course' is an anagram of 'ecurso'.
'ecurso' inserted inside 'rr' is 'recursor'.
'recursor' put after 'p' is 'PRECURSOR'.
(Other definitions for precursor that I've seen before include "Something going in advance of another" , "Man coming before me" , "Forebear" , "One coming before" , "harbinger of what is to follow" .)