Become fuzzy (4)
I believe the answer is:
blur
'become fuzzy' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for blur that I've seen before include "Make vague" , "Out-of-focus image" , "British rock group" , "Obscure; smudge" , "Britpop band - indistinct vision" .)