Maybe cool for half an hour in the shade (6)
I believe the answer is:
colour
'the shade' is the definition.
(I've seen this before)
'maybe cool for half an hour' is the wordplay.
'maybe' indicates an anagram.
'for' says to put letters next to each other.
'half' indicates taking half.
'hour' cut in half is 'ur'.
'cool' with letters rearranged gives 'colo'.
'colo'+'ur'='COLOUR'
'in' acts as a link.
(Other definitions for colour that I've seen before include "black?" , "Distort; blush; hue" , "See 10" , "'Tinge, hue (6)'" , "Go red" .)