Fast hit I had wanted (5)
I believe the answer is:
rapid
'wanted' is the definition.
Both the answer and definition are adjectives. Perhaps you can see an association between them that I can't see?
'fast hit i had' is the wordplay.
'fast hit' becomes 'rap' (I've seen this in other clues. I am not sure about the 'fast' bit.).
'i had' becomes 'id' (common contraction).
'rap'+'id'='RAPID'
(Other definitions for rapid that I've seen before include "Expeditious" , "Happening quickly" , "Brisk" , "moving fast" , "Swift, speedy" .)