Catching the sun is silly - downright crazy (6)
I believe the answer is:
insane
'downright crazy' is the definition.
'insane' can be an answer for 'crazy' (similar in meaning). I'm unsure of the 'downright' bit.
'catching the sun is silly' is the wordplay.
'catching' means one lot of letters goes inside another.
'the sun' becomes 'S' (abbreviation).
'is silly' becomes 'inane' (inane means silly or foolish).
's' placed into 'inane' is 'INSANE'.
Can you help me to learn more?
(Other definitions for insane that I've seen before include "Irresponsible" , "Mental" , "having a screw loose" , "mad for love?" , "Round the bend" .)