Pure smack that you and I must pick up (5)
I believe the answer is:
white
'pure' is the definition.
(I've seen this before)
'smack that you and i must pick up' is the wordplay.
I cannot really understand how this works, but
'smack' could be 'hit' (I've seen this in another clue) and 'hit' is located in the answer.
'you and i' could be 'we' and 'we' is found within the leftover letters.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for white that I've seen before include "Wit, he? (anag.)" , "Having pink skin" , "Pallid" , "The colour of snow" , "wine" .)