On the contrary, it's less attractive when it includes the decorative fringing (7)
I believe the answer is:
tassels
'attractive when it includes the decorative fringing' is the definition.
I can't judge whether this defines the answer.
'on the contrary it's less' is the wordplay.
'on' says to put letters next to each other.
'the' becomes 't' (the is pronounced as a 't' sound in some dialects).
'contrary' says the letters should be written in reverse.
'it' becomes 'sa' (old-fashioned abbreviation for sex appeal).
'less' becomes 'sels' (I can't justify this - if you can you should give a lot more credence to this answer).
'sa' in reverse letter order is 'as'.
't'+'as' is 'tas'.
'tas'+'sels'='TASSELS'
Can you help me to learn more?
(Other definitions for tassels that I've seen before include "Decorations" , "Adornments of bunches of cords" , "Tufts of decorative hanging threads" , "Ornamental bunches of cords" , "Ornamental bunches of threads as on curtains" .)