Six McRae's, one mixed grill (5-7)
I believe the answer is:
cross-examine
'grill' is the definition.
(thesaurus)
'six mcrae's one mixed' is the wordplay.
'mixed' indicates an anagram.
'six'+'mcraes'+'one'='sixmcraesone'
'sixmcraesone' anagrammed gives 'CROSS-EXAMINE'.
(Other definitions for cross-examine that I've seen before include "Forensically question" , "Question in court" , "Check evidence in court" .)