A lot must go on making this (7,5)
I believe the answer is:
reserve price
'a lot' is the definition.
Both the answer and definition are singular nouns.
Maybe there's an association between them I don't understand?
'must go on making this' is the wordplay.
I cannot quite see how this works, but
'go' could be 'serve' (serving is a kind of going) and 'serve' is found in the answer.
'on' could be 're' (regarding) and 're' is present in the answer.
The remaining letters 'price' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for reserve price that I've seen before include "value that may lead to a lot for relatively little" , "Bottom limit at auction" , "Minimum amount acceptable at auction" , "At an auction, the lowest acceptable bid" , "Lowest possible cost" .)