Canal features may be security devices (5)
I believe the answer is:
locks
I believe this clue is a double definition.
'canal features' is the first definition.
(I've seen this in another clue)
'security devices' is the second definition.
(I've seen this in another clue)
'may be' is the link.
(Other definitions for locks that I've seen before include "Secure fasteners for doors" , "Tresses" , "Clusters of hair" , "Canal features" , "Fastens - hair" .)