A good journalist makes use of anything they can learn from any news source — even unattributed ones.
Literal
Good newspaper-journalist [topic-は], whichever-donna-kind-of news-source [from-からも], specifically-source-unknown-type [of-の] news-source [from-からも], learn-take can thing [topic-は] anything utilizes.
A dense professional-ethics sentence. どんな~からも ('from any X at all') is a concessive universal. つまり ('in other words, that is') introduces a clarification. 学びとれる ('can learn and take') is the potential of the compound 学び取る. 何でも ('anything') as universal object.