Pool where idol swims (4)
I believe the answer is:
lido
'pool' is the definition.
(I've seen this in other clues)
'idol swims' is the wordplay.
'swims' indicates an anagram.
'idol' is an anagram of 'LIDO'.
'where' is the link.
(Other definitions for lido that I've seen before include "Italian bathing place" , "Outdoor swimming pool" , "Venetian resort" , "bathing facilities" , "Aquatic leisure centre" .)