They allow one to keep in touch with people (7)
I believe the answer is:
letters
'people' is the definition.
The definition and answer can be both related to communication as well as being plural nouns.
Perhaps they are linked in a way I don't understand?
'they allow one to keep in touch' is the wordplay.
I cannot quite understand how this works, but
'allow' could be 'let' (synonyms) and 'let' is present in the answer.
This explanation may well be incorrect...
'with' acts as a link.
Can you help me to learn more?
(Other definitions for letters that I've seen before include "Correspondence" , "They are bound to look after tenants" , "A, B, C, D etc" , "eg E G" , "Epistles" .)