Witch appearing with small goblin, before descending on ship (9)
I believe the answer is:
sorceress
'witch' is the definition.
(I know that witch can be written as sorceress)
'small goblin before descending on ship' is the wordplay.
'small' becomes 's' (abbreviation - e.g. clothes size).
'goblin' becomes 'orc' (goblin-like creatures in JRR Tolkien's books).
'before' becomes 'ere' (poetic term for 'before').
'descending on' says to put letters next to each other (in a down clue, some letters go on top of others).
'ship' becomes 'SS' (prefix in ship names eg SS Great Britain).
's'+'orc'+'ere'+'ss'='SORCERESS'
'appearing with' acts as a link.
(Other definitions for sorceress that I've seen before include "She spells" , "Witch" , "charming female" , "one who has magic powers" , "Female magician" .)