Edging, following stream (5)
I believe the answer is:
frill
'edging' is the definition.
(I have seen 'Ornamental edging' mean 'frill' so perhaps 'edging' could also mean 'frill')
'following stream' is the wordplay.
'following' becomes 'f' (used when citing page numbers etc).
'stream' becomes 'rill' (rill is a kind of stream).
'f'+'rill'='FRILL'
(Other definitions for frill that I've seen before include "Gathered material" , "Unnecessary embellishment" , "Gathered strip as a trimming" , "Ornamental edging" , "A decorative gathering of fabric" .)