Reign thus, badly and absolutely! (4,5)
I believe the answer is:
sure thing
'absolutely' is the definition.
(thesaurus)
'reign thus badly' is the wordplay.
'badly' indicates an anagram.
'reign'+'thus'='reignthus'
'reignthus' with letters rearranged gives 'SURE THING'.
'and' is the link.
(Other definitions for sure thing that I've seen before include "A certainty - I agree!" , "of course" , "cert" , "no chance of losing" .)