Child about to identify Mediterranean island (7)
I believe the answer is:
minorca
'mediterranean island' is the definition.
(I know that Minorca is a island)
'child about' is the wordplay.
'child' becomes 'minor' (synonyms).
'about' becomes 'ca' (abbreviation for circa).
'minor'+'ca'='MINORCA'
'to identify' is the link.
(Other definitions for minorca that I've seen before include "holiday island" , "One of Balearic islands" , "Mediterranean island" , "Balearic island (Eng. sp.)" , "Balearic island; O, cram in (anag.)" .)