Becomes stressed when the news editors are discontented (6)
I believe the answer is:
tenses
'becomes stressed' is the definition.
I can't judge whether this definition defines the answer.
'the news editors are discontented' is the wordplay.
'the' becomes 't' (the is pronounced as a 't' sound in some dialects).
'news' becomes 'ens' (I can't explain this - if you can you should give a lot more credence to this answer).
'are discontented' means to remove the middle letters (the word's contents are removed).
'editors' with its centre taken out is 'es'.
't'+'ens'+'es'='TENSES'
'when' is the link.
Can you help me to learn more?
(Other definitions for tenses that I've seen before include "Verb forms indicating time" , "Verb forms that indicate time" , "Past, present etc." , "Tightens up" , "'Past and present, say (6)'" .)