Director in new post unexpectedly seen to resign (4,4)
I believe the answer is:
step down
'to resign' is the definition.
(I've seen this before)
'director in new post unexpectedly' is the wordplay.
'director' becomes 'd'.
'in' means one lot of letters goes inside another.
'unexpectedly' indicates anagramming the letters.
'new'+'post'='newpost'
'newpost' is an anagram of 'stepown'.
'd' going within 'stepown' is 'STEP-DOWN'.
'seen' is the link.
(Other definitions for step down that I've seen before include "Get off one's soap-box" , "Give up or retire from a position" , "Leave office" , "Withdraw from" , "Give up office" .)