This is mostly likely a DM Discretion issue, but what follows is some guidance:
In order for Thunderwave to successfully push you 10' away from the ground, the Cleric would need to have done the following:
Depending on initiative order at the time of falling, there may not have been an opportunity to ready the action. For the sake of this discussion - there was sufficient time.
Cleric would need to fall first and be 'below' the party. This would allow him to "push" his party 10' up prior to hitting the ground.
The party would need to be directly above and in range of the Cleric. Your mileage may vary on how you interpret in range.
All party members would still have to make the save against it and take the 3d8 Thunder Damage (either full or half depending on save state.)Further discussion on saving throws can be found here.
If those conditions are met, then the question arises as to what happens.
The cleric would of course hit the ground with regular falling damage.
The party, after falling X feet, would now be pushed back up, only to fall back down final 10 feet to the ground.
From a pure calculation point, you have the original X distance, then they are pushed back up 10', only to fall again. The original fall is still occurring, but you have moved sent them back up 10' in order to fall.
It is unknown if falling damage is based purely on distance, or on an assumption of speed/momentum. However, given that the falling damage is calculated purely on distance, you have still falling the full distance, plus an additional 10' AND the thunder damage.
However - I think there is a case for saying the push 'resets' the falling meter and it's only 10 feet that they have fallen (if you timed it right after you hit the ground, but before your party does.)
This basically turns a Readied Thunderwave into a bit of a Featherfall. For a level One spell slot, I think this is reasonable as long as the first four conditions I listed are met.