Demands from former wife's decrees (6)
I believe the answer is:
exacts
'demands' is the definition.
(exacting is a kind of demanding)
'former wife's decrees' is the wordplay.
'former wife' becomes 'ex'.
'decrees' becomes 'acts' (I've seen this before).
'ex'+'acts'='EXACTS'
'from' is the link.
(Other definitions for exacts that I've seen before include "Insists on and obtains, say payment - sounds precise" , "Extorts" , "Insists on and obtains - sound precise" , "Insists on or claims" , "making demands" .)