Prohibits importing European seeds (5)
I believe the answer is:
beans
'seeds' is the definition.
(bean is a kind of seed)
'prohibits importing european' is the wordplay.
'prohibits' becomes 'bans' (banning is a kind of prohibiting).
'importing' is an insertion indicator.
'european' becomes 'e' (abbreviation e.g. EU).
'bans' going around 'e' is 'BEANS'.
(Other definitions for beans that I've seen before include "nuts" , "Edible kidney-shaped seeds" , "Haricots for instance" , "Nothing at all in US" , "Vegetables" .)