Does well when in favour of press reform (8)
I believe the answer is:
prospers
'does well' is the definition.
Although both the answer and definition are verbs in their -s form, I cannot see how they can define each other.
'in favour of press reform' is the wordplay.
'in favour of' becomes 'pro' (being pro a particular cause).
'reform' is an anagram indicator (letters in a new form).
'press' anagrammed gives 'spers'.
'pro'+'spers'='PROSPERS'
'when' is the link.
Can you help me to learn more?
(Another definition for prospers that I've seen is " Flourishes, thrives".)