Trump's last official address in high office (10)
I believe the answer is:
presidency
'high office' is the definition.
(high political office)
'trump's last official address' is the wordplay.
'last' indicates one should take the final letters.
'official address' becomes 'residency'.
The last letter of 'trump' is 'p'.
'p'+'residency'='PRESIDENCY'
'in' is the link.
(Other definitions for presidency that I've seen before include "top job?" , "US office" , "Top position" , "Monroe once took on" , "Office at the top" .)