Not yet manifest (6)
I believe the answer is:
latent
'not yet manifest' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for latent that I've seen before include "Existing but not yet manifest" , "Talent (anag)" , "Hidden, not manifest" , "Hidden but able to be developed" , "'Hidden, undeveloped (6)'" .)