Power of special constable to intercept drug smuggler (6)
I believe the answer is:
muscle
'power' is the definition.
(I've seen this before)
'special constable to intercept drug smuggler' is the wordplay.
'special constable' becomes 'SC' (abbreviation for special constable).
'to intercept' is an insertion indicator.
'drug smuggler' becomes 'mule' (I've seen this in other clues).
'sc' inserted within 'mule' is 'MUSCLE'.
'of' is the link.
(Other definitions for muscle that I've seen before include "Beef" , "Fibrous tissue with the ability to contract" , "meat" , "A contractile organ of the body" , "elevator, for instance" .)