Modern part of leisure centre (6)
I believe the answer is:
recent
'modern' is the definition.
(I've seen this before)
'part of leisure centre' is the wordplay.
'part of' indicates the answer is hidden within the clue.
'RECENT' is hidden within 'leisure centre'.
(Other definitions for recent that I've seen before include "Fresh - current" , "Having happened not long ago" , "Originating not long ago" , "Present day" , "Up-to-date" .)