Stop scratching head and vote for fraud (4)
I believe the answer is:
hoax
'for fraud' is the definition.
(synonyms)
'stop scratching head and vote' is the wordplay.
'stop' becomes 'whoa' (command to stop a horse).
'scratching head' means to remove the first letter (the word's head is removed).
'and' says to put letters next to each other.
'vote' becomes 'x' (how votes are marked).
'whoa' with its first letter taken off is 'hoa'.
'hoa'+'x'='HOAX'
(Other definitions for hoax that I've seen before include "A joking kind of deception" , "Imposture" , "Practical joke" , "A plan to deceive" , "Fake, such as Piltdown Man" .)