Request parking on meadow (4)
I believe the answer is:
plea
'request' is the definition.
(plea is a kind of request)
'parking on meadow' is the wordplay.
'parking' becomes 'p' (abbreviation on road signs).
'on' is a charade indicator (letters next to each other) (in a down clue, letters appear on others).
'meadow' becomes 'lea' (a lea is a grassy area).
'p'+'lea'='PLEA'
(Other definitions for plea that I've seen before include "Negotiation between prosecutor and defendant" , "(and 14) Enjoyment - gratification" , "Intercession" , "Urgent entreaty" , "Defendant's answer to a charge or claim" .)