Talk nonstop (7)
This might be a double definition.
'talk' is the first definition.
The definition and answer can be both acts as well as being singular nouns.
Perhaps you can see a link between them that I can't see?
'nonstop' is the second definition.
(I've seen this before)
Can you help me to learn more?
(Other definitions for express that I've seen before include "Fast train; specific" , "Put into words - high speed" , "Quick -- exact" , "Explicit" , "clear > couch" .)
(Another definition for runon that I've seen is " not using paragraphs?".)