One thousand dollars to preserve that hole in the ground (5,6)
I believe the answer is:
grand canyon
'hole in the ground' is the definition.
Both the answer and definition are singular nouns.
Maybe they are linked in a way I don't understand?
'one thousand dollars to preserve that' is the wordplay.
'one thousand dollars' becomes 'grand' (I've seen this in another clue).
'to preserve' becomes 'can' (canning is a kind of preserving).
'that' becomes 'yon' (archaic term meaning 'that').
'grand'+'can'+'yon'='GRAND CANYON'
Can you help me to learn more?
(Other definitions for grand canyon that I've seen before include "nickname of US State" , "Major feature in Arizona" , "Colorado River gorge" , "American gorge" , "Arizona tourist attraction" .)