Majestic part of picture gallery (5)
I believe the answer is:
regal
'majestic' is the definition.
(I know that majestic can be written as regal)
'part of picture gallery' is the wordplay.
'part of' says the answer is hidden in the clue.
'REGAL' can be found hidden inside 'picture gallery'.
(Other definitions for regal that I've seen before include "King's" , "fit for the Queen" , "befitting a king" , "Befitting a monarch" , "Like a queen?" .)