American idiot our group engaged in plot taking the wrong direction (5)

I believe the answer is:

dweeb

I'm a little stuck... Click here to teach me more about this clue!

'american idiot' is the definition.
'dweeb' can be an answer for 'idiot' (I've seen this before). I am not certain of the 'american' bit.

I don't understand how the rest of the clue works.

Can you help me to learn more?

(Other definitions for dweeb that I've seen before include "Antisocial guy" , "(US) idiot" , "Boringly studious student" , "techie bore?" , "Insignificant student" .)

I've seen this clue in The Independent.

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