Describing water-source from China, say, probed by European broadcaster (8)
I believe the answer is:
artesian
'describing water-source' is the definition.
(referring to a type of well)
'china say probed by european broadcaster' is the wordplay.
'china say' becomes 'asian' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'probed by' indicates putting letters inside (I've seen this in other clues).
'european broadcaster' becomes 'rte' (Irish TV channel RTE).
'asian' placed around 'rte' is 'ARTESIAN'.
'from' acts as a link.
(Other definitions for artesian that I've seen before include "(Well) fed by pressure" , "Type of well made from a sea train" , "Type of well that doesn't need a pump" , "A nastier sort of well, oddly" , "(Well) flowing under natural pressure" .)