Simple anagram clue in crossword, finally correct (5)
I believe the answer is:
emend
'correct' is the definition.
(I've seen this before)
'simple anagram clue in crossword finally' is the wordplay.
'finally' indicates one should take the final letters.
The final letters of 'simple anagram clue in crossword' are 'EMEND'.
(Other definitions for emend that I've seen before include "Edit; make alterations to a draft" , "make an improvement" , "Remove errors" , "Improve by editing" , "Correct/revise (a text)" .)