Set of buttons important at home (6)
I believe the answer is:
keypad
'set of buttons' is the definition.
'important at home' is the wordplay.
'important' becomes 'key' (similar in meaning).
'at' says to put letters next to each other.
'home' becomes 'pad' (pad can mean a person's home).
'key'+'pad'='KEYPAD'
(Other definitions for keypad that I've seen before include "Typing area on an electronic device" , "Perhaps remote" , "Data input device for computers etc" , "Phone's button array" , "What might help you calculate" .)