Colourful half hour hidden in cover (5)
I believe the answer is:
lurid
'colourful' is the definition.
Both the answer and definition are adjectives. Maybe there's an association between them I don't understand?
'half hour hidden in cover' is the wordplay.
'half' suggests halving the letters.
'hidden in' means one lot of letters goes inside another.
'cover' becomes 'lid' (lid is a kind of cover).
'hour' cut in half is 'ur'.
'ur' placed inside 'lid' is 'LURID'.
Can you help me to learn more?
(Other definitions for lurid that I've seen before include "Fiery - sensational" , "Explicit" , "Ghastly in appearance" , "In shocking detail" , "In vivid detail" .)