Squid's home (3)
I believe the answer is:
sea
'squid's home' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for sea that I've seen before include "7 [ship] s on this" , "The main" , "The Med, e.g." , "Caspian, e.g." , "The tide" .)