Society function at democratic partnership (5)
I believe the answer is:
stand
'partnership' is the definition.
(I've seen this before)
'society function at democratic' is the wordplay.
'society' becomes 's' (common abbreviation in names of organisations).
'function' becomes 'tan' (tangent, mathematical function).
'at' means one lot of letters go next to another.
'democratic' becomes 'd' (political abbreviation).
's'+'tan'+'d'='STAND'
(Other definitions for stand that I've seen before include "stay the same in position" , "Rise; bear" , "Remain upright" , "Be erect" , "remain in force" .)