With this system, the police have a burden to shoulder (6)
I believe the answer is:
method
'with this system' is the definition.
'method' can be an answer for 'system' (thesaurus). I'm not sure about the rest of the definition.
'the police have a burden to shoulder' is the wordplay.
I cannot quite understand how this works, but
an anagram of 'the' is 'eth' which is within the answer.
The remaining letters 'mod' is a valid word which might be clued in a way I don't understand.
This may be the basis of clue (or it may be nonsense).
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" .)