New latch - nice but complicated (9)
I believe the answer is:
technical
'complicated' is the definition.
(thesaurus)
'new latch nice' is the wordplay.
'new' indicates anagramming the letters.
'latch'+'nice'='latchnice'
'latchnice' is an anagram of 'TECHNICAL'.
'but' is the link.
(Other definitions for technical that I've seen before include "relating to a particular craft" , "Concerned with applied science" , "Relating to mechanical art or applied science" , "Scientific" , "Industrial" .)