Long time following stone steps (6)
I believe the answer is:
stages
'steps' is the definition.
(both can mean parts of a process)
'long time following stone' is the wordplay.
'long time' becomes 'ages' (I've seen this before).
'following' means one lot of letters go next to another.
'stone' becomes 'st' (abbreviation).
'ages' put after 'st' is 'STAGES'.
(Other definitions for stages that I've seen before include "Parts of route taken by bus" , "Platforms for performances" , "Fixes" , "Coaches" , "Positions or points in a process" .)