Active with Geoffrey in strong forward flow (6)
I believe the answer is:
onrush
'strong forward flow' is the definition.
(I've seen this in another clue)
'active with geoffrey' is the wordplay.
'active' becomes 'on' (I've seen this in other clues).
'with' means one lot of letters go next to another.
'geoffrey' becomes 'rush' (I can't justify this - if you can you should believe this answer much more).
'on'+'rush'='ONRUSH'
'in' is the link.
Can you help me to learn more?
(Other definitions for onrush that I've seen before include "Swarm" , "Forward dash" , "Forward surge" , "sudden swoop" , "Career" .)