Tropical tree in archetypal myth (4)
I believe the answer is:
palm
'tropical tree' is the definition.
(the palm tree)
'in archetypal myth' is the wordplay.
'in' indicates the answer is hidden within the clue.
'PALM' can be found hidden inside 'archetypal myth'.
(Other definitions for palm that I've seen before include "Sign of victory" , ""trophy"" , "Obscure" , "Date-tree" , "Tree symbolising victory" .)