Clue: In America, a slight girl coming out clutching the Guardian (5)
Answer: DWEEB
Explanation: Definition: In America, a slight
 DEB(short for "debutante", a girl coming out/being introduced to fashionable society) **containing**(clutching) WE(the presenter of this crossword, the Guardian using the plural self-referential pronoun).
Defn: …/an insult by calling someone a socially inept person.