I would put in now for top post (9)
I believe the answer is:
president
'top post' is the definition.
'President' can be an answer for 'post' (President is an example). I am not sure about the 'top' bit.
'i would put in now' is the wordplay.
'i would' becomes 'id'.
'put in' indicates putting letters inside.
'now' becomes 'present' (I've seen this before).
'id' inserted within 'present' is 'PRESIDENT'.
'for' is the link.
Can you help me to learn more?
(Other definitions for president that I've seen before include "2's official title" , "US leader" , "top man" , "Head, of a republic say" , "Head of college" .)