Tape is compulsory (7)
I believe the answer is:
binding
This could be a double definition.
'tape' is the first definition.
The definition and answer can be both man-made objects as well as being singular nouns.
Maybe you can see a link between them that I don't see?
'compulsory' is the second definition.
(thesaurus)
'is' acts as a link.
Can you help me to learn more?
(Other definitions for binding that I've seen before include "Mandatory" , "Obligatory" , "work for a bookmaker" .)