Friend hiding European ring (4)
I believe the answer is:
peal
'ring' is the definition.
(synonyms)
'friend hiding european' is the wordplay.
'friend' becomes 'pal' (pal is a kind of friend).
'hiding' indicates putting letters inside.
'european' becomes 'e' (abbreviation e.g. EU).
'pal' going around 'e' is 'PEAL'.
(Other definitions for peal that I've seen before include "Ring recurrently" , "Sound of bells, thunder" , "Loud ringing of bells" , "Deep prolonged sound" , "Leap up to loud ring of a bell" .)