Related to 50 and 500 (4)
I believe the answer is:
told
'related' is the definition.
(I've seen this in another clue)
'to 50 and 500' is the wordplay.
'50' becomes 'l' (Roman numeral).
'and' is a charade indicator (letters next to each other).
'500' becomes 'D' (Roman numeral for 500).
'to'+'l'+'d'='TOLD'
(Other definitions for told that I've seen before include "instructed" , "Related (a story)" , "Made an impact" , "Assured" , "Said" .)