Figure in poll a voter rejected (4)
I believe the answer is:
oval
'figure' is the definition.
(oval is a kind of figure)
'in poll a voter rejected' is the wordplay.
'in' indicates a hidden word.
'rejected' is a reversal indicator.
'lavo' is hidden in the letters of 'poll a voter'.
'lavo' backwards is 'OVAL'.
(Other definitions for oval that I've seen before include "Geometric shape" , "Egg-like" , "Squashed circle" , "Race track" , "sports ground" .)