A starlet is a nonsense word for a youngster who may or may not go on to be amazing. It is based on the principal that if you add -let to the end of any word it seems like a small version of it. Ducklet. Watchlet. Hamlet. Walletlet. Pamphlet.
Though obviously referring to a midget or dwarf star, the word starlet itself describes a sea anemone from the East Coast of the United States of America. Young footballers do not resemble these at all. They don't really move and spend hours anchored in the mud. Some have suggested Gavin McCann and Mark Kinsella spent large parts of their career anchored to the half-way line, but this remains unproven.
Intrisincally linked with 'big' clubs stealing youngsters off the poor (see Chelsea's tranfer window ban for illegally signing Gael Kakuta), it is often combined with ridiculous verbs normally used for hunting animals. This makes you so shocked you purchase a newspaper. The clubs often Swoop for a starlet, but they may also 'seal a deal' for, or even possibly 'land' one. Like the players a fucking blue finned tuna and big clubs are big bad fishermen. All the metaphors describe poor little babies being stolen by massive predators, though the link between 'seal a deal' and seal clubbing is yet to be verified.
Recently the definition has been widened to anyone vaguely young, rendering it utterly pointless. Yet it remains in use by most journalists in order to get people excited about virtually nothing. Whereas once all teams nicked players off rival youth systems and no-one really cared, Arsene Wenger's Arsenal made it fashionable and French to sign starlets. Now every fan in the land is made instantly excited by the 11 additional starlets they get to read about as well as the normal signings their club makes. The word was finally debased beyond all reason when Livingstone signed starlet Ewan Moyes from Hibs on the 28th August 2009.