In the rain an eyeshade is silly (5)
I believe the answer is:
inane
'silly' is the definition.
(I've seen this before)
'in the rain an eyeshade' is the wordplay.
'in' says the answer is hidden in the clue.
'INANE' is hidden in the letters of 'rain an eyeshade'.
'is' acts as a link.
(Other definitions for inane that I've seen before include "Mindlessly silly" , "Idiotic" , "Empty" , "Devoid of intelligence" , "Lacking sense, silly" .)