Deal with leader in Yemen, making pact (6)
I believe the answer is:
treaty
'pact' is the definition.
(I know that pact can be written as treaty)
'deal with leader in yemen' is the wordplay.
'deal with' becomes 'treat' (synonyms).
'leader in' says to take the initial letters.
The first letter of 'yemen' is 'y'.
'treat'+'y'='TREATY'
'making' is the link.
(Other definitions for treaty that I've seen before include "Formal agreement between governments" , "'Pact, accord (6)'" , "Pact, accord between states" , "Yatter (anag.)" , "Formal agreement between nations" .)