Sanction’s justifiable in leader’s absence (6)
I believe the answer is:
enable
'sanction's' is the definition.
(thesaurus)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for enable that I've seen before include "Facilitate or make possible" , "Render capable" , "Provide with means or opportunity" , "Authorise" , "Capacitate" .)