Boater, say, welcoming some home (7)
I believe the answer is:
habitat
'home' is the definition.
(thesaurus)
'boater say welcoming some' is the wordplay.
'boater say' becomes 'hat' (boater is a kind of hat).
'welcoming' means one lot of letters goes inside another (in sense of 'inviting in').
'some' becomes 'abit' (a bit ).
'hat' going around 'abit' is 'HABITAT'.
(Other definitions for habitat that I've seen before include "Shop founded by Terence Conran" , "Natural environment (of creature)" , "One's normal environment" , "Natural home and surroundings" , "Natural home of an organism" .)