A mob destroying last of Arab’s crops (6)
I believe the answer is:
arable
'a mob destroying last' is the definition.
I can't tell whether this defines the answer.
'arab's crops' is the wordplay.
'crops' becomes 'le' (I can't justify this - if you can you should give a lot more credence to this answer).
'arab'+'le'='ARABLE'
'of' acts as a link.
Can you help me to learn more?
(Other definitions for arable that I've seen before include "Of land, capable of growing crops" , "Fit for crop growing" , "Capable of being tilled" , "Of land, fit to be cultivated" , "farming land!" .)