Fair beauty burdened by sentiment (7)
I believe the answer is:
goodish
'fair' is the definition.
(thesaurus)
'beauty burdened by sentiment' is the wordplay.
'beauty' becomes 'dish' (slang term for an attractive person).
'burdened by' means one lot of letters go next to another (in a down clue, some letters are carried by others).
'sentiment' becomes 'goo' (goo can mean sentimentality).
'dish' after 'goo' is 'GOODISH'.
(Other definitions for goodish that I've seen before include "Quite acceptable" , "reasonable" .)