Depressed by an empty form in advance (4,7)
I believe the answer is:
down payment
'advance' is the definition.
The definition and answer can be both related to property as well as being singular nouns.
Perhaps they are linked in a way I don't understand?
'depressed by an empty form' is the wordplay.
'depressed' becomes 'down' (synonyms).
'by' means one lot of letters go next to another.
'form' is an anagram indicator (a different form of the same letters).
'an'+'empty'='anempty'
'anempty' with letters rearranged gives 'payment'.
'down'+'payment'='DOWN PAYMENT'
'in' acts as a link.
Can you help me to learn more?
(Other definitions for down payment that I've seen before include "first instalment" , "Deposit towards a purchase" , "Start of settlement" .)