Down payment expected to be over 500 (7)
I believe the answer is:
subdued
'down' is the definition.
(thesaurus)
'payment expected to be over 500' is the wordplay.
'payment' becomes 'sub' (I have seen 'Advance payment ' mean 'sub' so perhaps 'payment' could also mean 'sub').
'expected' becomes 'due' (similar in meaning).
'to be over' says to put letters next to each other.
'500' becomes 'D' (Roman numeral for 500).
'sub'+'due'+'d'='SUBDUED'
(Other definitions for subdued that I've seen before include "Quiet; repressed" , "'Restrained, low-key (7)'" , "reserved" , "Chastened" , "Quieted and brought under control" .)