Waste of time following stitch (6)
I believe the answer is:
sewage
'waste' is the definition.
(I know that sewage is a type of waste)
'time following stitch' is the wordplay.
'time' becomes 'age' (an age is a period of time).
'following' says to put letters next to each other.
'stitch' becomes 'sew' (synonyms).
'age' put after 'sew' is 'SEWAGE'.
'of' is the link.
(Other definitions for sewage that I've seen before include "Refuse carried off through drainage system" , "Drainage waste" , "Effluent" , "Refuse for drains" , "Effluence" .)