Parking fellow outside tree (5)
I believe the answer is:
maple
'tree' is the definition.
(I know that maple is a type of angiospermous tree)
'parking fellow outside' is the wordplay.
'parking' becomes 'p' (abbreviation on road signs).
'fellow' becomes 'male' (fellow is a term for a man).
'outside' indicates putting letters inside.
'p' inserted within 'male' is 'MAPLE'.
(Other definitions for maple that I've seen before include "Tree whose leaf features on the flag of Canada" , "Tree providing Canada's national emblem" , "Tree with syrupy sap" , "Syrup-yielding tree" , "Canadian flag leaf" .)