Word of agreement, it has you opening the useful facility (7)
I believe the answer is:
amenity
'useful facility' is the definition.
(I've seen this before)
'word of agreement it has you opening' is the wordplay.
'word of agreement' becomes 'amen' (I've seen this before).
'has' says to put letters next to each other.
'opening' suggests taking the first letters.
The initial letter of 'you' is 'y'.
'amen'+'it'+'y'='AMENITY'
'the' acts as a link.
(Other definitions for amenity that I've seen before include "Convenience - any time (anag)" , "Item provided to make life easier" , "type of hospital bed" , "Building's useful feature" , "Facility making life easy or pleasant - any time" .)