Rolling on a log in pool (6)
I believe the answer is:
lagoon
'pool' is the definition.
(I've seen this before)
'rolling on a log' is the wordplay.
'rolling' indicates anagramming the letters.
'on'+'a'+'log'='onalog'
'onalog' anagrammed gives 'LAGOON'.
'in' acts as a link.
(Other definitions for lagoon that I've seen before include "Body of salt water cut off from the sea" , "A salt-water lake enclosed by reef" , "Inland sea" , "Calm water behind reef" , "Atoll lake" .)