Compel by force (6)
I believe the answer is:
coerce
'compel by force' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for coerce that I've seen before include "Railroad" , "'Force, pressurise (6)'" , "Force, pressure" , "Persuade (the unwilling) by force" , "Oblige by force" .)