Understanding about European lament (4)
I believe the answer is:
keen
'lament' is the definition.
(keen is a kind of lament)
'understanding about european' is the wordplay.
'understanding' becomes 'ken' (I've seen this before).
'about' indicates putting letters inside.
'european' becomes 'e' (abbreviation e.g. EU).
'ken' placed around 'e' is 'KEEN'.
(Other definitions for keen that I've seen before include "Piercing" , "Eager; wail in grief" , "Agog" , "mourn for the departed" , "Eager, enthusiastic" .)