Unstressed syllable in school was cut (5)
I believe the answer is:
schwa
'unstressed syllable' is the definition.
The answer and definition can be both related to communication as well as being singular nouns.
Perhaps you can see an association between them that I can't see?
'school was cut' is the wordplay.
'school' becomes 'sch'.
'cut' means to remove the last letter.
'was' with its final letter taken off is 'wa'.
'sch'+'wa'='SCHWA'
'in' is the link.
Can you help me to learn more?
(Other definitions for schwa that I've seen before include "Uh' sound" , "Unstressed vowel (phonetics)" , "Indistinct sound" , "Stress-free sound" , "sound unstressed" .)