Training duo at nice complex (9)
I believe the answer is:
education
'training' is the definition.
('education' can be a synonym of 'training')
'duo at nice complex' is the wordplay.
'complex' indicates anagramming the letters.
'duo'+'at'+'nice'='duoatnice'
'duoatnice' with letters rearranged gives 'EDUCATION'.
(Other definitions for education that I've seen before include "Theory and practice of teaching" , "Knowledge acquired by learning and instruction" , "studies" , "training" , "an answer to all clues, initially" .)