Celebrity concerned with new gown goes topless (6)
I believe the answer is:
renown
'celebrity' is the definition.
(I know that celebrity can be written as renown)
'concerned with new gown goes topless' is the wordplay.
'concerned with' becomes 're' (re can mean regarding, concerning).
'new' becomes 'n' (common abbreviation eg NT for New Testament).
'goes topless' means to remove the first letter (I've seen 'go topless' mean this).
'gown' with its first letter taken away is 'own'.
're'+'n'+'own'='RENOWN'
(Other definitions for renown that I've seen before include "Fame, respect" , "Fame and eminence" , "Celebrity, fame" , "Fame and public acclamation" , "Fame and distinction" .)