Stoop to pick up large mixture (5)
I believe the answer is:
blend
'mixture' is the definition.
(blend is a kind of mixture)
'stoop to pick up large' is the wordplay.
'stoop' becomes 'bend' (I've seen this in another clue).
'to pick up' is an insertion indicator.
'large' becomes 'L' (eg in clothes sizes).
'bend' going around 'l' is 'BLEND'.
(Other definitions for blend that I've seen before include "Mix together" , "Mingle" , "union" , "Fusion" , "Merge" .)