Thatcher, for one, in element before terms in Foreign Office (9)
I believe the answer is:
leaderene
'thatcher for one' is the definition.
I don't know anything about this answer so I can't tell whether it can be defined by this definition.
'element before terms in foreign office' is the wordplay.
'element' becomes 'lead' (lead is a kind of element).
'before' becomes 'ere' (poetic term for 'before').
'terms in' suggests the final letters (I've seen 'term in' mean this (term can mean the end of something)).
The last letters of 'foreign office' are 'ne'.
'lead'+'ere'+'ne'='LEADERENE'
'in' is the link.
Can you help me to learn more?
(Other definitions for leaderene that I've seen before include "PM's nickname" , "Maggie originally" .)