Become subject to (5)
I believe the answer is:
incur
'become subject to' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for incur that I've seen before include "Bring on oneself, say costs" , "Become liable to (something) through one's actions" , "Enter into" , "contract" , "Fall liable to" .)