One left to cut south back to commit a crime (5)
I believe the answer is:
heist
'a crime' is the definition.
(heist is a kind of crime)
'one left to cut south back to commit' is the wordplay.
'one left' says the letters should be written backwards.
'cut' means to remove the last letter.
'back' indicates one should take the final letters (the letter at the back).
'to' says to put letters next to each other (I've seen this in other clues).
'commit' becomes 'sie' (I am not sure about this - if you are sure you should believe this answer much more).
The final letter of 'south' is 'h'.
'to' with its final letter removed is 't'.
'h' after 'sie' is 'sieh'.
't'+'sieh'='tsieh'
'tsieh' back-to-front is 'HEIST'.
Can you help me to learn more?
(Other definitions for heist that I've seen before include "crime?" , "Robbery, often at gunpoint" , "Armed hold-up (sl.)" , "Mugging" , "Audacious robbery" .)