OECD chief explodes at national leaders as this rises? (5)
I believe the answer is:
ocean
'this rises?' is the definition.
(as in rising sea levels)
'oecd chief explodes at national leaders' is the wordplay.
'leaders' says to take the initial letters.
The first letters of 'oecd chief explodes at national' is 'OCEAN'.
'as' acts as a link.
(Other definitions for ocean that I've seen before include "Large stretch of water" , "tons of water" , "A lot of water!" , "An immense expanse of sea" , "It's pretty wet!" .)