Plant - Maserati touring around one (9)
I believe the answer is:
artemisia
'plant' is the definition.
The answer is an example.
'maserati touring around one' is the wordplay.
'touring' is an anagram indicator (touring can mean moving around).
'around' is an insertion indicator.
'one' becomes 'i' (Roman numeral).
'maserati' anagrammed gives 'artemsia'.
'artemsia' enclosing 'i' is 'ARTEMISIA'.
(Other definitions for artemisia that I've seen before include "Aromatic plant related to wormwood" , "genus of plants" , "strong-smelling bush?" , "species of plant" , "Medicinal herb" .)