Pair from Australia caught importing advanced drug (6)
I believe the answer is:
prozac
'drug' is the definition.
(I've seen this before)
'pair from australia caught importing advanced' is the wordplay.
'pair from' becomes 'prc' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'australia' becomes 'oz' (informal name for Australia).
'caught' means one lot of letters goes inside another.
'importing' is an insertion indicator.
'advanced' becomes 'a' (abbreviation).
'prc' placed around 'oz' is 'prozc'.
'prozc' placed around 'a' is 'PROZAC'.
Can you help me to learn more?
(Other definitions for prozac that I've seen before include "Anti-depressant trade mark" , "Common antidepressant drug" , "Controversial antidepressant" , "Upper" , "medication" .)