Affected material finally deleted (4)
I believe the answer is:
twee
'affected' is the definition.
(I've seen this before)
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for twee that I've seen before include "Sickly sweet" , "Sentimentally sweet" , "Mawkish" , "Rather too pretty" , "Overly precious" .)