It orbits Neptune before appearing in November papers (6)
I believe the answer is:
nereid
'it orbits neptune' is the definition.
(a moon of the planet Neptune)
'before appearing in november papers' is the wordplay.
'before' becomes 'ere' (poetic term for 'before').
'appearing in' means one lot of letters goes inside another.
'november' becomes 'N' (phonetic alphabet: alpha, bravo, charlie etc.).
'papers' becomes 'ID' (identification papers).
'n'+'id'='nid'
'ere' inserted inside 'nid' is 'NEREID'.
(Other definitions for nereid that I've seen before include "Mythological sea nymph" , "End ire (anag) - sea nymph" , "Bristle worm" , "Sea-nymph" , "Sea nymph in greek mythology (6)" .)