Extravagant six amid ridicule (6)
I believe the answer is:
lavish
'extravagant' is the definition.
(synonyms)
'six amid ridicule' is the wordplay.
'six' becomes 'VI' (Roman numerals).
'amid' is an insertion indicator.
'ridicule' becomes 'lash'.
'vi' inserted into 'lash' is 'LAVISH'.
(Other definitions for lavish that I've seen before include "Plentiful or extravagent" , "Unstinting" , "Profusely generous" , "Prodigal - unrestrained" , "Splendid" .)