Check remainder ahead of wet weather (8)
I believe the answer is:
restrain
'check' is the definition.
(synonyms)
'remainder ahead of wet weather' is the wordplay.
'remainder' becomes 'rest' (synonyms).
'ahead of' is a charade indicator (letters next to each other) (some letters go in front of others).
'wet weather' becomes 'rain' (rain is wet weather).
'rest'+'rain'='RESTRAIN'
(Other definitions for restrain that I've seen before include "bottle up" , "Stop" , "Control - check" , "stay" , "Keep in check" .)