Cephalopod (7)
I believe the answer is:
octopus
'cephalopod' is the definition.
(I know that octopus is a type of octopod)
This is the entire clue.
(Other definitions for octopus that I've seen before include "Far-reaching organisation" , "Cephalopod mollusc" , "person with widespread influence" , "Tentacled sea creature" , "Sea creature with tentacles" .)