Correct spaces before last word (5)
I believe the answer is:
emend
'correct' is the definition.
(I've seen this in another clue)
'spaces before last word' is the wordplay.
'spaces' becomes 'em en' (as in em and en spaces in printing).
'before' is a charade indicator (letters next to each other).
'last' suggests the final letters.
The final letter of 'word' is 'd'.
'emen'+'d'='EMEND'
(Other definitions for emend that I've seen before include "Alter something written to correct errors" , "Remove errors" , "Revise (a text) (E, not A)" , "would appear better" , "Make improvements or corrections" .)