After most of race, men finally keel over (6)
I believe the answer is:
careen
'keel over' is the definition.
'after most of race men finally' is the wordplay.
'after' says to put letters next to each other.
'most of' means to remove the last letter.
'race' becomes 'career' (I've seen this before).
'men finally' becomes 'n' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'career' with its last letter removed is 'caree'.
'caree'+'n' is 'CAREEN'.
(Other definitions for careen that I've seen before include "List, heel over to one side" , "Turn" , "Tilt to one side" .)