Farm crop may be good with wet weather (5)
I believe the answer is:
grain
'farm crop' is the definition.
'good with wet weather' is the wordplay.
'good' becomes 'g' (abbreviation).
'with' is a charade indicator (letters next to each other).
'wet weather' becomes 'rain' (I've seen this before).
'g'+'rain'='GRAIN'
'may be' acts as a link.
(Other definitions for grain that I've seen before include "Single piece of sand etc" , "Smallest measure of weight in avoirdupois" , "Character" , "Small piece of sand" , "Small particle - wood texture" .)