At this place in the register (4)
I believe the answer is:
here
'at this place' is the definition.
(here in this place)
'in the register' is the wordplay.
'in' says the answer is hidden in the clue.
'HERE' is hidden in the letters of 'the register'.
(Other definitions for here that I've seen before include "Present - at this point" , "Hither" , ""___ be dragons" (old map inscription?)" , "At this stage" , "In attendance" .)