Reach great heights (4)
I believe the answer is:
soar
'reach great heights' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for soar that I've seen before include "Rise high in flight" , "'Fly, glide (4)'" , "Fly high, Leicester river" , "Rise; sounds like painful" , "Rise quickly" .)