Run round tree, creating quite an impression (6)
I believe the answer is:
flashy
'quite an impression' is the definition.
I can't judge whether this definition defines the answer.
'run round tree' is the wordplay.
'run' becomes 'fly' (I am not sure about this - if you are sure you should believe this answer much more).
'round' indicates putting letters inside.
'tree' becomes 'ash' (ash is a kind of tree).
'fly' enclosing 'ash' is 'FLASHY'.
'creating' acts as a link.
Can you help me to learn more?
(Other definitions for flashy that I've seen before include "Loud" , "Showy but empty; Has fly (anag.)" , "Garish" , "Vulgar" , "Cheaply ostentatious" .)