Nymph originally nameless before getting identification (6)
I believe the answer is:
nereid
'nymph' is the definition.
(Nereid is an example)
'originally nameless before getting identification' is the wordplay.
'originally' says to take the initial letters.
'before' becomes 'ere' (usually literary**).
'getting' means one lot of letters go next to another.
'identification' becomes 'id'.
The initial letter of 'nameless' is 'n'.
'n'+'ere'+'id'='NEREID'
(Other definitions for nereid that I've seen before include "Sea-nymph" , "Sea nymph in greek mythology (6)" , "End ire (anag) - sea nymph" , "Bristle worm" , "Mythological sea nymph" .)