Relative value finally found in Mediterranean city (5)
I believe the answer is:
niece
'relative' is the definition.
(niece is a kind of relative)
'value finally found in mediterranean city' is the wordplay.
'finally' says to take the final letters.
'found in' is an insertion indicator.
'mediterranean city' becomes 'nice' (I've seen this in other clues).
The last letter of 'value' is 'e'.
'e' going within 'nice' is 'NIECE'.
(Other definitions for niece that I've seen before include "Family relation" , "Family relative" , "Son's cousin" , "Family girl" , "Brother or sister's daughter" .)