Plot scam with father to seize power (8)
I believe the answer is:
conspire
'plot' is the definition.
(conspiring is a kind of plotting)
'scam with father to seize power' is the wordplay.
'scam' becomes 'con' (I've seen this before).
'with' is a charade indicator (letters next to each other).
'father' becomes 'sire' ('sire' can be a synonym of 'father'**).
'to seize' means one lot of letters goes inside another.
'power' becomes 'p'.
'sire' going around 'p' is 'spire'.
'con'+'spire'='CONSPIRE'
(Other definitions for conspire that I've seen before include "implicated in plot" , "Secretly plan together" , "Collude" , "Act secretly with others" , "Plot together - on prices (anag)" .)