Airport parking area (5)
I believe the answer is:
'airport parking area' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for apron that I've seen before include "Airport area for manoeuvring and loading planes" , "Protective garment (with strings attached!)" , "Pinafore" , "Cook's garment" , "Cook's protector" .)