Docile character accepting English downpour, the idiot (9)

I believe the answer is:

lamebrain

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'the idiot' is the definition.
(I've seen this before)

'docile character accepting english downpour' is the wordplay.
'docile character' becomes 'lamb' (I can't explain this - if you can you should give a lot more credence to this answer).
'accepting' is an insertion indicator (inserted letters are accepted).
'english' becomes 'E' (abbreviation as in OED).
'downpour' becomes 'rain' (pouring rain).
'lamb' placed around 'e' is 'lameb'.
'lameb'+'rain'='LAMEBRAIN'

Can you help me to learn more?

(Other definitions for lamebrain that I've seen before include "two [TOMFOOL] ..." , "fool" , "Idiot" , "turkey" , "Nelly" .)

I've seen this clue in The Guardian.

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