Mass above Pluto rising? Neptune, perhaps (3,3)
I believe the answer is:
sea-god
'neptune perhaps' is the definition.
(I know that Neptune is a sea god)
'mass above pluto rising?' is the wordplay.
I cannot really see how this works, but
'pluto' could be 'god' (Pluto was a Roman god) and 'god' is found in the answer.
The remaining letters 'sea' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
Can you help me to learn more?
(Another definition for sea-god that I've seen is " Neptune or Poseidon".)