A new version of user interface, finally is designed (7)
I believe the answer is:
reissue
'a new version' is the definition.
(I've seen this before)
'user interface finally is designed' is the wordplay.
'finally' suggests the final letters.
'designed' indicates an anagram (designed with the letters).
The last letter of 'interface' is 'e'.
'user'+'e'+'is'='usereis'
'usereis' with letters rearranged gives 'REISSUE'.
'of' acts as a link.
(Other definitions for reissue that I've seen before include "Republish" , "get book brought out again" , "New edition of book" , "Put out old material" , "New book version" .)