Crossword Genius

Astounded by stupid son on lorry (10)

Ross

I believe the answer is:

dumbstruck

'astounded' is the definition.
(thesaurus)

'stupid son on lorry' is the wordplay.
'stupid' becomes 'dumb' ('dumb' can be similar in meaning to 'stupid'**).
'son' becomes 's'.
'on' is a charade indicator (letters next to each other).
'lorry' becomes 'truck' (I've seen this before).
'dumb'+'s'+'truck'='DUMBSTRUCK'

'by' acts as a link.

(Other definitions for dumbstruck that I've seen before include "Temporarily deprived of speech by shock" , "Gobsmacked" , "Speechless with amazement" .)

I've seen this clue in The Telegraph.
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