Monarch crossing street to see cattle thief (7)
I believe the answer is:
rustler
'cattle thief' is the definition.
(synonyms)
'monarch crossing street' is the wordplay.
'monarch' becomes 'ruler' (I've seen this in another clue).
'crossing' is an insertion indicator (to cross can mean to go over or around).
'street' becomes 'st' (abbreviation).
'ruler' going around 'st' is 'RUSTLER'.
'to see' is the link.
(Other definitions for rustler that I've seen before include "Cattle-thief" , "person taking stock" , "Cattle stealer" , "one whose stock-taking is dishonest" , "Stealer of livestock" .)