Relative in European resort, by the sound of it? (5)
I believe the answer is:
niece
'relative' is the definition.
(type of relative)
'european resort by the sound of it?' is the wordplay.
'european resort' becomes 'Nice' (French coastal resort).
'by the sound of it?' indicates a 'sounds like' (homophone) clue.
'nice' is a homophone of 'NIECE'.
'in' acts as a link.
(Other definitions for niece that I've seen before include "Young female relative" , "Brother's girl" , "Daughter of a sibling" , "A sibling's daughter" , "Family girl" .)