Two mods peddle a punk do (6)
I believe the answer is:
mohawk
'a punk do' is the definition.
The definition and answer can be both related to communication as well as being singular nouns.
Maybe you can see a link between them that I can't see?
'two mods peddle' is the wordplay.
'two mods' becomes 'mo' (I am not sure about this - if you are sure you should believe this answer much more).
'peddle' becomes 'hawk' (synonyms).
'mo'+'hawk'='MOHAWK'
Can you help me to learn more?
(Other definitions for mohawk that I've seen before include "Skating manoeuvre - member of Amerindian tribe" , "American runner" , "Native American - punk hairdo" , "Iroquoian native" , "(N Amer.) Indian" .)