Cultured person losing head (4)
I believe the answer is:
arty
'cultured' is the definition.
(I've seen this before)
'person losing head' is the wordplay.
'person' becomes 'party' (eg an individual in a court case).
'losing head' means to remove the first letter.
'party' with its initial letter taken off is 'ARTY'.
(Other definitions for arty that I've seen before include "Boho" , "Bohemian" , "Having exaggerated air of aesthetic interests" , "pretentiously cultivated" , "Culturally creative" .)