Picture painted initially by false traitor (8)
I believe the answer is:
portrait
'picture' is the definition.
(portrait is a type of picture)
'painted initially by false traitor' is the wordplay.
'initially' says to take the initial letters.
'by' is a charade indicator (letters next to each other).
'false' is an anagram indicator.
The initial letter of 'painted' is 'p'.
'traitor' with letters rearranged gives 'ortrait'.
'p'+'ortrait'='PORTRAIT'
(Other definitions for portrait that I've seen before include "One picture" , "Painting of a real person" , "(Person's) painting" , "Head/shoulders painting" , "Type of painting" .)