Sanction law to maintain production of cider (8)
I believe the answer is:
accredit
'sanction' is the definition.
(thesaurus)
'law to maintain production of cider' is the wordplay.
'law' becomes 'act' (I've seen this before).
'to maintain' indicates putting letters inside.
'production of' indicates anagramming the letters.
'cider' anagrammed gives 'credi'.
'act' enclosing 'credi' is 'ACCREDIT'.
(Other definitions for accredit that I've seen before include "Officially recognise" , "Give authority or sanction to" , "Authorise (a diplomat) to hold a post" , "Endorse" , "Attribute (something to)" .)