Warden to limit means of access (5,3)
I believe the answer is:
screw cap
'of access' is the definition.
The definition suggests a singular noun which matches the answer.
'warden to limit' is the wordplay.
'warden' becomes 'screw' (I can't justify this - if you can you should believe this answer much more).
'to limit' becomes 'cap' (capping is a kind of limiting).
'screw'+'cap'='SCREW-CAP'
'means' is the link.
Can you help me to learn more?
(Other definitions for screw cap that I've seen before include "Secure bottle top" , "One to be twisted off bottle" , "One turned in opening" , "Bottle or jar top" .)