Scoundrel seizing power is transported (4)
I believe the answer is:
rapt
'transported' is the definition.
(I've seen this before)
'scoundrel seizing power' is the wordplay.
'scoundrel' becomes 'rat' (I've seen this in other clues).
'seizing' indicates putting letters inside.
'power' becomes 'p'.
'rat' placed around 'p' is 'RAPT'.
'is' acts as a link.
(Other definitions for rapt that I've seen before include "Part being transported" , "Ecstatic - engrossed" , "Very attentive" , "Enchanted in part" , "'Transported, entranced (4)'" .)