Brings into play authorities shorn of power (6)
I believe the answer is:
exerts
'brings into play' is the definition.
'authorities shorn of power' is the wordplay.
'authorities' becomes 'experts'.
'shorn of' is a deletion indicator.
'power' becomes 'p'.
'experts' with 'p' removed is 'EXERTS'.
(Other definitions for exerts that I've seen before include "Makes strenuous effort" , "Makes use of" , "Brings into use, say strength" , "Brings into use or to bear" , "Brings something to bear forcefully" .)