Crack in ruby fixed (8)
I believe the answer is:
resolved
'fixed' is the definition.
(thesaurus)
'crack in ruby' is the wordplay.
'crack' becomes 'solve' (crack can mean to solve or decipher).
'in' indicates putting letters inside.
'ruby' becomes 'red' (synonyms).
'solve' going within 'red' is 'RESOLVED'.
(Other definitions for resolved that I've seen before include "Firmly determined" , "Settled; determined" , "Not put off" , "tackled crossword again?" , "very firm" .)