Copy European drug smuggler importing a source of this (7)
I believe the answer is:
Here is my best explanation:
'copy' is the definition.
(I've seen this before)
'european drug smuggler importing a source of this' is the wordplay.
'european' becomes 'e' (abbreviation e.g. EU).
'drug smuggler' becomes 'mule' (I've seen this before).
'importing' is an insertion indicator.
'source of' indicates taking the first letters.
The first letter of 'this' is 't'.
'mule' placed around 'at' is 'mulate'.
(Other definitions for emulate that I've seen before include "Copy - rival", "Try to do as well as another", "Contend with", "Try to be equal or better than", "Try to be like", "Compete", "Try to do as well as, follow example", "Ape", "Imitate, try to equal" and "Strive to equal or surpass".)