If exposed, won’t rain, try broadcasting (2,3)
I believe the answer is:
on air
'broadcasting' is the definition.
(I've seen this before)
'if exposed won't rain try' is the wordplay.
I cannot really see how this works, but
an anagram of 'rain' is 'nair' which is within the answer.
A single letter 'o' remains which might be clued in a way I don't see.
This may be the basis of clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for on air that I've seen before include "Broadcasting at this moment" , "Radio show might be" , "Broadcasting live" , "very happily?" , "now showing" .)