Milkshake insert (5)
I believe the answer is:
straw
'milkshake insert' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for straw that I've seen before include "What a sucker gets given" , "Residue of cereal crop" , "In the wind, it's an indication" , "Residue of threshed corn" , "Means to absorb" .)