Ground floor chamber to make ready for office (5)
I believe the answer is:
groom
'ready for office' is the definition.
'groom' can be an answer for 'ready' (I've seen this before). I am unsure of the 'for office' bit.
'ground floor chamber' is the wordplay.
'ground floor' becomes 'g' (I can't explain this - if you can you should believe this answer much more).
'chamber' becomes 'room' (I've seen this before).
'g'+'room'='GROOM'
'to make' acts as a link.
Can you help me to learn more?
(Other definitions for groom that I've seen before include "Stable-hand" , "Person taking care of horses (or getting married?)" , "Attendant for horses" , "Coach" , "Stable attendant" .)