I agree, German police not content it's a prank (4)
I believe the answer is:
jape
'a prank' is the definition.
(I've seen this in another clue)
'i agree german police not content it's' is the wordplay.
I cannot quite see how this works, but
'i' could be 'a' and 'a' is present in the answer.
'it' could be 'e' ('e' can mean 'electronic' which is similar to 'IT') and 'e' is located in the answer.
The remaining letters 'jp' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for jape that I've seen before include "Kid" , "Trick - joke - jest" , "Lark" , "Jolly wheeze" , "Practical joke, jest" .)