Fancy popular gallery having racist leader in charge! (9)
I believe the answer is:
intricate
'fancy' is the definition.
(similar in meaning)
'popular gallery having racist leader in charge' is the wordplay.
'popular' becomes 'in'.
'gallery' becomes 'tate' (Tate Modern, Tate Britain etc).
'having' means one lot of letters goes inside another.
'leader' suggests taking the first letters.
'in charge' becomes 'ic' (abbreviation for 'in charge').
The first letter of 'racist' is 'r'.
'r'+'ic'='ric'
'tate' going around 'ric' is 'tricate'.
'in'+'tricate'='INTRICATE'
(Other definitions for intricate that I've seen before include "ornate" , "puzzling" , "Convoluted" , "puzzlingly obscure" , "Entangled" .)