Scale of a second century death (6)
I believe the answer is:
ascend
'scale' is the definition.
(thesaurus)
'a second century death' is the wordplay.
'a second' becomes 'as' (I've seen this in other clues).
'century' becomes 'c' (common abbreviation).
'death' becomes 'end' ('end' can be a synonym of 'death').
'as'+'c'+'end'='ASCEND'
'of' is the link.
(Other definitions for ascend that I've seen before include "Come up" , "Take off" , "Get higher" , "Make the top" , "Travel upwards" .)