File the brief communication (4)
I believe the answer is:
line
I believe this is a triple definition!
'file' is the first definition.
(thesaurus)
'the brief' is the second definition.
(thesaurus)
'communication' is the third definition.
(line is a kind of communication)
(Other definitions for line that I've seen before include "Family" , "Row - occupation" , "Long mark; direction" , "(Skin) wrinkle; limit" , "dash one end to the other" .)