Dominate in wet weather report (5)
I believe the answer is:
reign
'dominate' is the definition.
(I know that dominate can be written as reign)
'wet weather report' is the wordplay.
'wet weather' becomes 'rain' (rain is wet weather).
'report' indicates a 'sounds like' (homophone) clue.
'rain' sounds like 'REIGN'.
'in' acts as a link.
(Other definitions for reign that I've seen before include "Hegemony" , "Hold sway, rule" , "Rule of monarch" , "Sit on a throne" , "Time on throne" .)