Concern, changing NHS timetables (13)
I believe the answer is:
establishment
'concern' is the definition.
(I've seen this before)
'changing nhs timetables' is the wordplay.
'changing' indicates anagramming the letters.
'nhs'+'timetables'='nhstimetables'
'nhstimetables' anagrammed gives 'ESTABLISHMENT'.
(Other definitions for establishment that I've seen before include "system" , "Action of setting up on a permanent basis" , "concern" , "ruling body!" , "powers that be" .)