If so, loser becomes poser, in a manner of speaking (4)
I believe the answer is:
lisp
'speaking' is the 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?
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for lisp that I've seen before include "Non-standard pronunciation" , "Have difficulty pronouncing `s'" , "Thpeak like thith" , "Speak with defective sibilants" , "Slip into speech defect" .)