Artist, once more back in front, falls (7)
I believe the answer is:
niagara
'falls' is the definition.
(thesaurus)
'artist once more back in front' is the wordplay.
'artist' becomes 'ra' (Royal Academician, member of Royal Academy of Arts).
'once more' becomes 'again' ('again' can be a synonym of 'once more').
'back' says the letters should be written in reverse.
'in front' means one lot of letters go next to another.
'again' reversed gives 'niaga'.
'ra' put after 'niaga' is 'NIAGARA'.
(Other definitions for niagara that I've seen before include "North American waterfall" , "It falls in North America" , "They fall in North America" , "Waterfall at Iran aga" , "River forming part of US-Canada border" .)