Trick for one party Democrat backs (5)
I believe the answer is:
dodge
'trick' is the definition.
(I've seen this before)
'for one party democrat backs' is the wordplay.
'for one' becomes 'eg' (both can mean 'for example').
'party' becomes 'do' (do can informally mean a party).
'democrat' becomes 'd'.
'backs' is a reversal indicator.
'eg'+'do'+'d'='egdod'
'egdod' back-to-front is 'DODGE'.
(Other definitions for dodge that I've seen before include "Wild West city" , "Step sideways to evade" , "Elude, sidestep" , "Wheeze" , "Move quickly out of the way of" .)