gated echo

Did a quick search for this, was sure someone would have done it, but didn't find anything.  What I want is echo that comes in after the singing phrase ends.  So the singing stays clear but then discrete echos (not reverb) happen afterwards.  A la Pink Floyd.  Surely someone has patched up an effect to do this.
 
CAF

I did with piano track on one my songs. What I did was 1. Add the Sonitus:fx Delay plugin onto a new buss track. 2. On the piano track I created a send to the delay buss track. I then used automation on the piano track control to control the delay send to only send to the delay buss when I wanted the echo effect.

The Sonitus gate can sidechain too

You can use side chain. If I were to do it I think I would route a send to the echo buss and automate the send enable/disable.

  If I understand what you are trying to do, I would cut the words that you want echo on into separate clips and then apply echo directly to the clips effect bin or drag those clips to there own track and add delay to that track

@Chewing

Keep in mind that you can automate the send to a bus as well as the volume fader on the bus itself.

So, one easy way to manually do this is to select the bus with the delay on it and swipe in the lower half of the track during verses and reduce the volume of the delay to where you want it. Then bring it up between with a nice slide. If you hover your mouse pointer at the top of the track over a selected region you can click and drag and envelope nodes will be added at either end of the selection making this easy.

A side-effect of this method is that you will get whatever words in your delay that were sung.

If you do this instead with the send level, you have strict control over the volumes of certain words, regardless of where they might fall in the delay. So a low priority word can be ping ponging left and right at a low volume and a high priority word can ping pong more strongly without raising the lingering volume of the low priority word.