Person stealing money (6)
I believe the answer is:
nicker
'money' is the definition.
(I've seen this before)
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for nicker that I've seen before include "Pound (slang)" , "One stealing" , "Someone who steals (a pound?)" , "One steals" , "Sound made by horse" .)