Slightly overestimate assembly (7)
I believe the answer is:
roundup
This clue could be a double definition.
'slightly overestimate' is the first definition.
The definition and answer can be both related to communication as well as being singular nouns.
Perhaps they are linked in a way I don't understand?
'assembly' is the second definition.
(thesaurus)
Can you help me to learn more?
(Other definitions for roundup that I've seen before include "Gather together" , "Gathering of cattle or summary" , "Collection of facts" , "Gather into one place, animals or people" , "Summary (of events)" .)