Gosh! Southern European birds! (5)
I believe the answer is:
geese
'birds' is the definition.
(goose is a kind of bird)
'gosh southern european' is the wordplay.
'gosh' becomes 'gee' (I've seen this before**).
'southern' becomes 's' (abbreviation).
'european' becomes 'e' (abbreviation e.g. EU).
'gee'+'s'+'e'='GEESE'
(Other definitions for geese that I've seen before include "They come in gaggles and skeins" , "Sixth day of Christmas gift" , "Honking birds" , "wingers" , "Simpletons" .)