Crossword Genius

Dear me, shaken by the idealist's rousing start! (7)

Ross

I believe the answer is:

dreamer

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'rousing start' is the definition.
Although both the answer and definition are singular nouns, I can't understand how one could define the other.

'dear me shaken by the idealist's' is the wordplay.
'shaken' is an anagram indicator.
'by' is a charade indicator (letters next to each other).
'the idealist's' becomes 'r' (I can't justify this - if you can you should believe this answer much more).
'dear'+'me'='dearme'
'dearme' is an anagram of 'dreame'.
'dreame'+'r'='DREAMER'

Can you help me to learn more?

(Other definitions for dreamer that I've seen before include "Mitty type" , "One lost in abstraction" , "One who tends to live in an unreal world" , ""You may say I'm a __" (John Lennon)" , "Martin Luther King" .)

I've seen this clue in the Evening Standard.
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