When we say goodbye, not stopping (7)
I believe the answer is:
ongoing
'when we' is the definition.
I can't tell whether this definition defines the answer.
'goodbye not stopping' is the wordplay.
'goodbye' becomes 'on' (I can't justify this - if you can you should believe this answer much more).
'not stopping' becomes 'going' ('go' is the opposite to 'stop').
'on'+'going'='ONGOING'
'say' is the link.
Can you help me to learn more?
(Other definitions for ongoing that I've seen before include "Not yet concluded" , "Still in progress" , "still in operation" , "Continuing to exist or progress" , "Currently happening" .)