Maybe cool for half an hour in the shade (6)
I believe the answer is:
colour
'shade' is the definition.
(I've seen this before)
'maybe cool for half an hour' is the wordplay.
'maybe' indicates anagramming the letters.
'for' says to put letters next to each other.
'half an' indicates taking half.
'hour' with half the letters taken is 'ur'.
'cool' is an anagram of 'colo'.
'colo'+'ur'='COLOUR'
'in the' 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" .)