Rain is unfortunate for the audience (4)
I believe the answer is:
pour
'rain' is the definition.
(I've seen this before)
'unfortunate for the audience' is the wordplay.
'unfortunate' becomes 'poor' ('poor' can be similar in meaning to 'unfortunate').
'for the audience' shows a homophone (sound like).
'poor' is a homophone of 'POUR'.
'is' acts as a link.
(Other definitions for pour that I've seen before include "to drop, when it's heavy" , "(Of rain) fall heavily" , "Cause to flow or rain heavily" , "Cause to flow in a stream" , "16 [CATS AND DOGS]" .)