Detect end of democracy by clairvoyance (4)
I believe the answer is:
espy
'detect' is the definition.
(thesaurus)
'end of democracy by clairvoyance' is the wordplay.
'end of' says to take the final letters.
'by' says to put letters next to each other.
'clairvoyance' becomes 'esp' ('esp' can be a synonym of 'clairvoyance').
The last letter of 'democracy' is 'y'.
'y' after 'esp' is 'ESPY'.
(Other definitions for espy that I've seen before include "Spot; observe" , "Detect" , "Perceive" , "Catch sight of (poetic)" , "Pick out at a distance" .)