Licence to flog shiny material (6,7)
I believe the answer is:
patent leather
'shiny material' is the definition.
'licence to flog' is the wordplay.
'licence' becomes 'patent' (I've seen this before).
'to flog' becomes 'leather' (I can't justify this - if you can you should give a lot more credence to this answer).
'patent'+'leather'='PATENT LEATHER'
Can you help me to learn more?
(Other definitions for patent leather that I've seen before include "it will present a varnished surface" , "shiny skin" , "Tanned animal skin made hard and glossy" , "Varnished hide" , "Glossy shoe material" .)