Does it make the bank secure? (4,4)
I believe the answer is:
reef knot
'does it make the' is the definition.
I can't tell whether this defines the answer.
'bank secure?' is the wordplay.
'bank' becomes 'reef' (I've seen this before).
'secure?' becomes 'knot' (I've seen this before).
'reef'+'knot'='REEF-KNOT'
(Other definitions for reef knot that I've seen before include "One's tied up securely" , "Something to secure sails" , "Secure tie" , "Secure rope fastening" , "Fastening used by sailors" .)