Celebrity entertained by wicked person with sinister sign (7)
I believe the answer is:
bastard
'person with sinister sign' is the definition.
(sinister in the heraldic sense)
'celebrity entertained by wicked' is the wordplay.
'celebrity' becomes 'star' (I've seen this before).
'entertained by' indicates putting letters inside (inserted letters are hosted or entertained).
'wicked' becomes 'bad' (associated in meaning).
'star' going within 'bad' is 'BASTARD'.
(Other definitions for bastard that I've seen before include "scoundrel" , "villain" .)