Power shower audible? (5)
I believe the answer is:
'power' is the definition.
'shower audible?' is the wordplay.
'shower' becomes 'rain' (synonyms).
'audible?' shows a homophone (sound like) (I've seen 'audible' mean this).
'rain' is a homophone of 'REIGN'.
(Other definitions for reign that I've seen before include "Control", "time in power", "period in power", "Govern", "Niger (anag)".)