There is a big difference claret&blue
In straight clues, the WHOLE clue leads to the answer.
In cryptic clues, the definition is at the start or the end and the rest of the clue gives a second way of arriving at the answer.
Here, I was thinking the definition is 'Most effective' = TELLING (as in 'a telling remark'
The second part 'way of using information', could also be TELLING, ie passing on information.
BTW It would be really strange if the clue always followed the answers! lol