Negative remark, or lack of response (2,7)
I believe the answer is:
no comment
'lack of response' is the definition.
The definition suggests a singular noun which matches the answer.
'negative remark' is the wordplay.
'negative' becomes 'no' (no is a kind of negative).
'remark' becomes 'comment' (synonyms).
'no'+'comment'='NO COMMENT'
'or' is the link.
Can you help me to learn more?
(Other definitions for no comment that I've seen before include "Common reply to reporters" , "I wouldn't like to say" , "Rebuff to reporters" , "I'm not answering" , "I couldn't say" .)