Extravagant? Wrong again! (5)
I believe the answer is:
outre
'extravagant?' is the definition.
(outre can mean extravagant or eccentric)
'wrong again' is the wordplay.
'wrong' becomes 'out' (eg a calculation might be 'out').
'again' becomes 're' (prefix meaning 'again').
'out'+'re'='OUTRE'
(Other definitions for outre that I've seen before include "Far out - in France" , "Weird" , "Strange" , "Abnormal" , "appear eccentric" .)