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 in another clue). I'm unsure of the remainder of the definition.
'with this system the police have' is the wordplay.
'with' is an insertion indicator.
'this system' is an anagram indicator (another version or system with the same letters).
'police have' becomes 'mod' (I can't explain this - if you can you should give a lot more credence to this answer).
'the' is an anagram of 'eth'.
'eth' placed 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" .)