When journalists are involved, even free beer is a downer (9)

'beer is a downer' is the definition.
I know nothing about this answer so I can't judge whether it can be defined by this definition.

'when journalists are involved even free' is the wordplay.
'when' becomes 're' (I can't justify this - if you can you should believe this answer much more).
'journalists' becomes 'press' (the press can mean the newspaper industry).
'are involved' indicates an anagram (involved can mean confusing or complex).
'even' indicates alternate letters (even-numbered letters are used).
The alternate letters of 'free' are 're'.
're' is an anagram of 'er'.
're'+'press'+'er'='REPRESSER'

Can you help me to learn more?