Item of data on popular type of drug (6)
I believe the answer is:
statin
'type of drug' is the definition.
'statin' can be an answer for 'drug' (type of drug). I am not sure about the 'type of' bit.
'item of data on popular' is the wordplay.
'item of data' becomes 'stat' (I can't justify this - if you can you should give a lot more credence to this answer).
'on' is a charade indicator (letters next to each other) (in a down clue, letters appear on others).
'popular' becomes 'in' ('in' can mean trendy).
'stat'+'in'='STATIN'
Can you help me to learn more?
(Other definitions for statin that I've seen before include "Cholesterol-reducing drug" , "Drug reducing cholesterol" , "Cholesterol-lowering drug" , "Drug given to reduce blood cholesterol" .)