Anxious uncertainty getting lift could develop into spitefulness (8)
I believe the answer is:
suspense
'anxious uncertainty' is the definition.
(I've seen this before)
I don't understand how the remainder of the clue works.
(Other definitions for suspense that I've seen before include "Excited anticipation of approaching climax" , "The 3 of having to wait" , "State of uncertainty or excitement" , "Seen puss (anag.)" , "Doubt" .)