The flower of auto-land? (9)
I believe the answer is:
carnation
'the flower' is the definition.
(carnation is a kind of flower)
'auto-land?' is the wordplay.
'auto' becomes 'car' (synonyms).
'land?' becomes 'nation' ('nation' can be a synonym of 'land').
'car'+'nation'='CARNATION'
'of' is the link.
(Other definitions for carnation that I've seen before include "Feature of many a wedding" , "Not in a car (anag) - plant" , "Oscar Wilde wore a green one" , "Anoint car with the strange flower" , "Flower like pink" .)