In the communication, seem worried about a gas leak (7)
I believe the answer is:
message
'gas leak' is the definition.
The definition and answer can be both related to communication as well as being singular nouns.
Maybe you can see a link between them that I don't see?
'in the communication seem worried about a' is the wordplay.
'in the' is an insertion indicator.
'communication' becomes 'sg' (I can't explain this - if you can you should believe this answer much more).
'worried' indicates anagramming the letters.
'about' means one lot of letters goes inside another.
'seem' is an anagram of 'mese'.
'sg' placed within 'mese' is 'messge'.
'messge' enclosing 'a' is 'MESSAGE'.
Can you help me to learn more?
(Other definitions for message that I've seen before include "meaning" , "Errand" , "Verbal or written communication" , "Brief communication" , "Communication that is sent" .)