Racket inside building (3)
I believe the answer is:
din
'racket' is the definition.
(thesaurus)
'inside building' is the wordplay.
'inside' indicates a hidden word.
'DIN' is hidden within 'building'.
(Other definitions for din that I've seen before include "'Continuous, unpleasant noise (3)'" , "Loud noise, racket" , "A lot of noise (3)" , "Clamour" , "Hubbub" .)