Ban retired setter, boozer with zest (7)
I believe the answer is:
embargo
'ban' is the definition.
(I know that embargo is a more specific form of ban)
'retired setter boozer with zest' is the wordplay.
'retired' says the letters should be written in reverse.
'setter' becomes 'me' (the setter of the clue).
'boozer' becomes 'bar'.
'with' says to put letters next to each other.
'zest' becomes 'go' (I can't justify this - if you can you should give a lot more credence to this answer).
'me' in reverse letter order is 'em'.
'em'+'bar'+'go'='EMBARGO'
Can you help me to learn more?
(Other definitions for embargo that I've seen before include "Order intended to prevent trade" , "Legal stoppage of commerce" , "Ban, veto" , "Government order imposing a trade barrier" , "Block" .)