Noisy thief? (7)
I believe the answer is:
rustler
'thief' is the definition.
(rustler is a kind of thief)
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for rustler that I've seen before include "Stock taker?" , "Cattle-thief" , "Horse thief" , "lawbreaker" , "person taking stock" .)