Article fifty covered by Times well (4)
I believe the answer is:
ably
'well' is the definition.
(thesaurus)
'article fifty covered by times' is the wordplay.
'article' becomes 'a' (indefinite article).
'fifty' becomes 'l' (roman numeral).
'covered by' is an insertion indicator.
'times' becomes 'by' (I've seen this in other clues).
'l' going into 'by' is 'bly'.
'a'+'bly'='ABLY'
(Other definitions for ably that I've seen before include "In proficient manner" , "Competently" , "With competence" , "In a competent fashion" , "In capable manner" .)