Water teeming down plain leaves no impression (5,4)
I believe the answer is:
falls flat
'leaves no impression' is the definition.
The definition and answer can be both to do with social activities as well as being verbs in their -s form.
Perhaps they are linked in a way I don't understand?
'water teeming down plain' is the wordplay.
I cannot quite understand how this works, but
'water' could be 'falls' (falls is a kind of water) and 'falls' is located in the answer.
'plain' could be 'flat' (flat is a kind of plain) and 'flat' is present in the answer.
This accounts for all the letters.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for falls flat that I've seen before include "Leaves one cold" , "Bombs" .)