Remove weapons from leaders of uprising nationalist association requesting munitions (5)
I believe the answer is:
unarm
'remove weapons from' is the definition.
(I've seen this before)
'leaders of uprising nationalist association requesting munitions' is the wordplay.
'leaders of' indicates taking the first letters.
The initial letters of 'uprising nationalist association requesting munitions' is 'UNARM'.
(Other definitions for unarm that I've seen before include "Disable" , "Remove weaponry from" , "Make harmless" , "Deactivate" , "Take weapons from (someone)" .)