Try this mixture when parched (7)
I believe the answer is:
thirsty
'parched' is the definition.
(I've seen this in another clue)
'try this mixture' is the wordplay.
'mixture' indicates an anagram.
'try'+'this'='trythis'
'trythis' with letters rearranged gives 'THIRSTY'.
'when' acts as a link.
(Other definitions for thirsty that I've seen before include "Ardently desiring" , "Keen" , "Needing moisture" , "Dry" , "Hungry" .)