With this system, the police have a burden to shoulder (6)
I believe the answer is:
method
'with this system the police have a burden to shoulder' is the definition.
'method' can be an answer for 'system' (I've seen this before). I am unsure of the rest of the definition.
'with this system the police have' is the wordplay.
'with' is an insertion indicator.
'this system' indicates an anagram (another version or system with the same letters).
'police have' becomes 'mod' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'the' with letters rearranged gives 'eth'.
'eth' put within 'mod' is 'METHOD'.
Can you help me to learn more?
(Other definitions for method that I've seen before include "Systematic way of doing something" , "rule" , "Way of doing something, perhaps in madness" , "Orderliness; procedure" , "Type of acting" .)