Maybe top criminal seizing power (7)
I believe the answer is:
spinner
'maybe top' is the definition.
'spinner' can be an answer for 'top' (as in a spinning top). I'm not sure about the 'maybe' bit.
'criminal seizing power' is the wordplay.
'criminal' becomes 'sinner' (someone who has done bad deeds).
'seizing' is an insertion indicator (inserted letters are seized).
'power' becomes 'p' (symbol in physics).
'sinner' placed around 'p' is 'SPINNER'.
Can you help me to learn more?
(Other definitions for spinner that I've seen before include "I make deliveries turning" , "Slow bowler - used to catch a mackerel?" , "revolutionary ball" , "Slow bowler - lure for mackerel" , "One delivering" .)