A greeting for everyone in the house (5)
I believe the answer is:
hallo
'a greeting' is the definition.
(alternative to hello)
'everyone in the house' is the wordplay.
'everyone' becomes 'all' (all people).
'in the' means one lot of letters goes inside another.
'house' becomes 'ho' (abbreviation for house).
'all' going within 'ho' is 'HALLO'.
'for' is the link.
(Other definitions for hallo that I've seen before include "greeting" , "I say" , "First indication" , "everyone in house" , "welcoming for visitors?" .)