Clammy part of Rwandan kingdom (4)
I believe the answer is:
dank
'clammy' is the definition.
('dank' can be a synonym of 'clammy')
'part of rwandan kingdom' is the wordplay.
'part of' says the answer is hidden in the clue.
'DANK' is hidden in the letters of 'rwandan kingdom'.
(Other definitions for dank that I've seen before include "Unpleasantly wet and cold" , "Chilly and clammy" , "Clammy, damp" , "Unpleasantly cool and damp" , "(Of atmosphere) wet and unpleasant" .)