Power of the police? (5)
I believe the answer is:
force
I believe this clue is a double definition.
'power' is the first definition.
(I know that power can be written as force)
'the police?' is the second definition.
(the force can refer to the police force)
'of' acts as a link.
(Other definitions for force that I've seen before include "Royal Air - -" , "Physical coercion" , "Compel, oblige" , "Violence" , "Energy" .)