Eight-armed sea creature (7)
I believe the answer is:
octopus
'eight-armed sea creature' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for octopus that I've seen before include "Sea creature's tentacles served as food" , "Long-tentacled creature" , "Far-reaching organisation" , "One well-armed" , "Cops out (anag.)" .)