Leader of party's lax about closure of remote office (8)
I believe the answer is:
premises
'office' is the definition.
'leader of party's lax about closure of remote' is the wordplay.
'leader of' indicates taking the first letters.
'lax' becomes 'remiss' (I've seen this before).
'about' indicates putting letters inside.
'closure of' indicates one should take the final letters.
The first letter of 'partys' is 'p'.
The final letter of 'remote' is 'e'.
'remiss' placed around 'e' is 'remises'.
'p'+'remises'='PREMISES'
(Other definitions for premises that I've seen before include "States" , "Assumptions" , "Property" , "The aforesaid" , "Business buildings" .)