Have a strong desire to achieve something (6)
I believe the answer is:
aspire
'have a strong desire to achieve something' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for aspire that I've seen before include "Have ambition or desire for praise" , "Set your sights on" , "Is a rep (anag.)" , "Have a strong desire to reach an objective" , "Yearn, dream (towards)" .)