Noble is 1, 2, 3, 4, say, after 5? (8)
I believe the answer is:
viscount
'noble' is the definition.
(I've seen this before)
'is 1 2 3 4 say after 5?' is the wordplay.
'1 2 3 4 say' becomes 'count'.
'after' says to put letters next to each other.
'5?' becomes 'v' ('v' can be a synonym of '5').
'is'+'count'='iscount'
'iscount' put after 'v' is 'VISCOUNT'.
(Other definitions for viscount that I've seen before include "plane" , "Lord" , "Minor peer" , "British peer" , "Nobleman" .)