Criminal in trouble, run in by US city's Republican leader (7)
I believe the answer is:
burglar
'criminal in trouble' is the definition.
'burglar' can be an answer for 'criminal' (burglar is a kind of criminal). I am not certain of the 'in trouble' bit.
'run in by us city's republican leader' is the wordplay.
'run in by' becomes 'burg' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'us city' becomes 'la'.
'leader' indicates taking the first letters.
The first letter of 'republican' is 'r'.
'burg'+'la'+'r'='BURGLAR'
Can you help me to learn more?
(Other definitions for burglar that I've seen before include "He takes" , "House thief" , "One breaking in" , "House robber" , "Building robber" .)