Exotic lady in Rio captivating king, by and large (10)
I believe the answer is:
ordinarily
'by and large' is the definition.
(thesaurus)
'exotic lady in rio captivating king' is the wordplay.
'exotic' indicates anagramming the letters.
'captivating' is an insertion indicator (I've seen this in other clues).
'king' becomes 'r' (r is abbreviation for rex).
'lady'+'in'+'rio'='ladyinrio'
'ladyinrio' is an anagram of 'odinarily'.
'odinarily' placed around 'r' is 'ORDINARILY'.
(Other definitions for ordinarily that I've seen before include "As a rule" , "In the usual run of things" , "following the custom" .)