At home, dates are used as a substitute (7)
I believe the answer is:
instead
'as a substitute' is the definition.
(I've seen this before)
'at home dates are used' is the wordplay.
'at' means one lot of letters go next to another.
'home' becomes 'in' ('he's home' can mean 'he's in').
'are used' is an anagram indicator.
'dates' is an anagram of 'stead'.
'in' put next to 'stead' is 'INSTEAD'.
(Other definitions for instead that I've seen before include "In place (of)" , "for a change" , "Alternatively" , "as an alternative option" , "In lieu" .)