Fellow at four gets royal note (5)
I believe the answer is:
fiver
'note' is the definition.
(I know that fiver is a type of note)
'fellow at four gets royal' is the wordplay.
'fellow' becomes 'f' (abbreviation - of a society etc.).
'at' means one lot of letters go next to another.
'four' becomes 'IV' (Roman numerals for four).
'gets' says to put letters next to each other.
'royal' becomes 'er' (abbreviation for Elizabeth Regina).
'f'+'iv'+'er'='FIVER'
(Other definitions for fiver that I've seen before include "Bank note" , "paper ready" , "Smallest English note" , "Banknote (informal)" , "money" .)