Wise half yields and formally withdraws (7)
I believe the answer is:
secedes
'formally withdraws' is the definition.
(I've seen this in another clue)
'wise half yields' is the wordplay.
'half' indicates taking half.
'yields' becomes 'cedes' ('cede' can be a synonym of 'yield').
'wise' with half the letters taken is 'se'.
'se'+'cedes'='SECEDES'
'and' is the link.
(Other definitions for secedes that I've seen before include "makes a withdrawal" , "Breaks away" , "Withdraws from an organization" .)