What kind of instrument resounds from the beginning of the song and it sounds like some oriental harmonica from Hawaii ?
Kalimba (I referenced the Korg M1 Kalimba)
All those new Bass/Deep/Garage/UK House artist feature a lot of FM synthesis sounds. So it might be a FM recreation of the Kalimba or other Woodblock Instrument.
On the other hand, since Clean Bandit consist of a DJ/Producer + 4 String Players it might just be a real Kalimba.
Who knows how exactly they made it, but if you go for some Mallet/Woodblock Intruments like Kalimba or Marimba you will find something you like. (Btw layering Those things with a E Piano sounds amazing!)
my guess is a soft mallet marimba patch on a keyboard or VI, but not a Kalimba (although Kalimbas are awesome this doesn't sound like one)
to go more ethnic but stay with wood you might try a balafon tuned chromatic.
Kalimbas are metal on wood and have a different attack and tone than what is in this song. With that said, if you listen, the producer filters or adjusts the attack of the instrument patch right before the vocals drop.
it's also clear by the way and notes that he plays off the top that it is played on a keyboard, not the real thing.