Hail Roman supporting Republican Party (4)
I believe the answer is:
rave
'party' is the definition.
(type of dance party)
'hail roman supporting republican' is the wordplay.
I cannot really understand how this works, but
'hail' could be 'ave' (greeting in Latin) and 'ave' is present in the answer.
'republican' could be 'r' (political abbreviation) and 'r' is found in the answer.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for rave that I've seen before include "Talk incoherently" , "Party with electronic dance music - be wild" , "Lively party" , "Rage" , "Rant - noisy, all-night party" .)