Follow laws enforced with police backing (5)
I believe the answer is:
swale
'police backing' is the definition.
The definition suggests a singular noun which matches the answer.
'follow laws enforced' is the wordplay.
I cannot really see how this works, but
an anagram of 'laws' is 'swal' which is within the answer.
A single letter 'e' remains which might be clued in a way I don't understand.
This explanation may well be incorrect...
'with' is the link.
Can you help me to learn more?
(Another definition for swale that I've seen is " Shade".)