Spot a line missing in voting paper (4)
I believe the answer is:
blot
'spot' is the definition.
(I know that spot can be written as blot)
'a line missing in voting paper' is the wordplay.
'a' becomes 'per' (eg 'one a day' means 'one per day').
'line' becomes 'rope' (line can mean a piece of rope).
'missing' indicates named letters should be taken away.
'in' indicates putting letters inside.
'voting paper' becomes 'blt' (I am not sure about this - if you are sure you should believe this answer much more).
'rope' with 'per' taken away is 'o'.
'o' inserted inside 'blt' is 'BLOT'.
Can you help me to learn more?
(Other definitions for blot that I've seen before include "Stain (on one's character?)" , "Soak up (ink); blemish" , "Blemish made with ink" , "Smudge (on escutcheon?)" , "Ink mark" .)