Aim at high things (6)
I believe the answer is:
aspire
'aim at high things' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for aspire that I've seen before include "Have ambitions (to achieve something)" , "I spare (anag.)" , "Yearn, dream (towards)" , "Aim, shoot for" , "Have an ambitious plan or a lofty goal" .)