Turns as otter turns (7)
I believe the answer is:
'turns' is the definition.
(rotating is a kind of turning)
'as otter turns' is the wordplay.
'turns' indicates an anagram.
'asotter' is an anagram of 'ROTATES'.
(Other definitions for rotates that I've seen before include "revolves" , "Turns round" , "Spins round" , "Takes turns" , "Turns around an axis" .)