Mount outdoor entertainment, rain not expected (3,4)
I believe the answer is:
set fair
'rain not expected' is the definition.
I know nothing about this answer so I cannot tell whether it can be defined by this definition.
'mount outdoor entertainment' is the wordplay.
'mount' shows that the letters should be reversed in order (I've seen 'mounted' mean this).
'outdoor' becomes 'tes' (I can't justify this - if you can you should believe this answer much more).
'entertainment' becomes 'fair' (as in a fun fair).
'tes' reversed gives 'set'.
'set'+'fair'='SET-FAIR'
Can you help me to learn more?
(Other definitions for set fair that I've seen before include "Seeming problem-free - barometer being high" , "Likely to remain fine or profitable" , "settled" , "Such is a good weather forecast" , "with bright prospects" .)