Freezing zone vacated following payment or backing (7)
I believe the answer is:
subzero
'freezing' is the definition.
(I've seen this before)
'zone vacated following payment or backing' is the wordplay.
'vacated' says to hollow out the word (remove centre letters) (internal letters vacate the word).
'following' is a charade indicator (letters next to each other).
'payment' becomes 'sub' (I have seen 'Advance payment ' mean 'sub' so perhaps 'payment' could also mean 'sub').
'backing' is a reversal indicator.
'zone' with its middle taken out is 'ze'.
'or' back-to-front is 'ro'.
'ze' put after 'sub' is 'subze'.
'subze'+'ro'='SUBZERO'
(Other definitions for subzero that I've seen before include "Extremely nippy" , "Colder than freezing" , "Less than 0" , "very cold" , "Negative" .)