Farcical advertisement about empty transport going to old city (6)
I believe the answer is:
absurd
'farcical' is the definition.
(thesaurus)
'advertisement about empty transport going to old city' is the wordplay.
'advertisement' becomes 'ad' ('ad' can be a synonym of 'advertisement').
'about' indicates putting letters inside.
'empty transport going' becomes 'bs' (I can't justify this - if you can you should give a lot more credence to this answer).
'to old city' becomes 'ur' (ancient city state).
'bs'+'ur'='bsur'
'ad' placed around 'bsur' is 'ABSURD'.
Can you help me to learn more?
(Other definitions for absurd that I've seen before include "Preposterous, nonsensical" , "Ludicrous, silly" , "Foolish, quite ridiculous" , "Idiotic" , "Ridiculous, quite nonsensical" .)