Matures, holds on, and settles (6)
I believe the answer is:
agrees
'settles' is the definition.
The definition and answer can be both to do with communicating as well as being verbs in their -s form.
Perhaps they are linked in a way I don't understand?
'matures holds on' is the wordplay.
'matures' becomes 'ages' ('age' can be a synonym of 'mature').
'holds' is an insertion indicator.
'on' becomes 're' ('on' can be mean 'with reference to').
'ages' going around 're' is 'AGREES'.
'and' acts as a link.
Can you help me to learn more?
(Other definitions for agrees that I've seen before include "is in accord" , "Assents, concurs" , "Accedes or concurs" , "Is of one mind" , "Shakes hands" .)