Pay out as an underwriter (9)
I believe the answer is:
subscribe
'pay' is the definition.
The answer and definition can be both to do with communicating as well as being verbs in their base form.
Maybe you can see a link between them that I can't see?
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for subscribe that I've seen before include "Receive on a regular basis, magazine say" , "Pay money regularly for, say, magazine" , "Give regular payments" , "Contribute money" , "Put one's name down as a purchaser" .)