Eastern European turns up with iodine in medicine bottles (5)
I believe the answer is:
vials
'medicine bottles' is the definition.
(I've seen this in another clue)
'eastern european turns up with iodine' is the wordplay.
'eastern european' becomes 'slav' (the Slavs are a European people).
'turns up' says the letters should be written backwards.
'with' means one lot of letters goes inside another.
'iodine' becomes 'I' (I is the chemical symbol for iodine).
'slav' back-to-front is 'vals'.
'vals' placed around 'i' is 'VIALS'.
'in' is the link.
(Other definitions for vials that I've seen before include "Small glass containers" , "Vessels" , "Small bottle that contains a drug" , "Ampoules" , "Small bottles of medicine" .)