Overly large but useful computer interface (7)
I believe the answer is:
toolbar
'useful computer interface' is the definition.
I don't know anything about this answer so I cannot tell whether it can be defined by this definition.
'overly large but' is the wordplay.
'overly' becomes 'too' ('too' can be a synonym of 'overly').
'large' becomes 'l'.
'but' becomes 'bar' (both can mean 'excluding' or 'except').
'too'+'l'+'bar'='TOOLBAR'
Can you help me to learn more?
(Other definitions for toolbar that I've seen before include "Set of computer icons, clicked on for functions" , "A selection of icons" , "Strip of function icons on screen" , "onscreen utility" , "Line on screen" .)