Office where duty’s arranged (5)
I believe the answer is:
study
'office' is the definition.
(I've seen this before)
'duty's arranged' is the wordplay.
'arranged' indicates an anagram (letters rearranged).
'dutys' is an anagram of 'STUDY'.
'where' is the link.
(Other definitions for study that I've seen before include "Read up - academic work" , "Den - learning" , "Work-room" , "Read to learn" , "Something worth observing" .)