V & A acquires original piece of Tiffany (7)
I believe the answer is:
against
'v' is the definition.
(v means versus in sports fixtures)
'a acquires original piece of tiffany' is the wordplay.
'acquires' becomes 'gains' (gaining is a kind of acquiring).
'original piece of' indicates taking the first letters.
The first letter of 'tiffany' is 't'.
'a'+'gains'+'t'='AGAINST'
(Other definitions for against that I've seen before include "Placed in direct contact with" , "Opposing" , "In conflict with" , "Not supporting" , "Opposite to" .)