Become liable to maintain curfew is holding (5)
I believe the answer is:
incur
'become liable' is the definition.
(I've seen this before)
'maintain curfew is holding' is the wordplay.
'is holding' indicates a hidden word.
'INCUR' is hidden in the letters of 'maintain curfew'.
'to' acts as a link.
(Other definitions for incur that I've seen before include "Become liable to (something) through one's actions" , "Bring on as a consequence" , "Attract" , "Lay oneself open to" , "Become subject to (penalty)" .)