Wife and I had to purchase device (6)
I believe the answer is:
widget
'device' is the definition.
(I know that widget is a type of device)
'wife and i had to purchase' is the wordplay.
'wife' becomes 'w' (abbreviation).
'and' says to put letters next to each other.
'i had' becomes 'i'd' (contraction).
'to purchase' becomes 'get'.
'w'+'id'+'get'='WIDGET'
(Other definitions for widget that I've seen before include "Unspecified device" , "Useful device for a particular job?" , "Small mechanical device" , "gizmo" , "Beer-can device" .)