Writing nothing breathlessly (6)
I believe the answer is:
noting
'writing' is the definition.
The definition and answer can be both to do with communicating as well as being present participle verbs.
Maybe you can see an association between them that I can't see?
'nothing breathlessly' is the wordplay.
'nothing' becomes 'no' (similar in meaning).
'breathlessly' becomes 'ting' (I can't explain this - if you can you should believe this answer much more).
'no'+'ting'='NOTING'
Can you help me to learn more?
(Other definitions for noting that I've seen before include "Making brief record of something" , "Recording in writing" , "Seeing" , "Observing or taking down" , "Making brief record as memory aid" .)