Majestic European prince appearing regularly (4)
I believe the answer is:
epic
'majestic' is the definition.
(both can mean grand)
'european prince appearing regularly' is the wordplay.
'european' becomes 'E' (abbreviation e.g. EU).
'appearing regularly' means one should take alternating letters.
The alternate letters of 'prince' are 'pic'.
'e'+'pic'='EPIC'
(Other definitions for epic that I've seen before include "Long poem, book, film" , "major work" , "Long story telling of a hero's deeds" , "long poem telling of heroic deeds" , "Long, heroic story" .)