Language error makes son drop back (4)

I believe the answer is:

lisp

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'language' is the definition.
(LISP is an example)

'error makes son drop back' is the wordplay.
'error makes' becomes 'li' (I can't justify this - if you can you should believe this answer much more).
'son' becomes 's'.
'back' says to take the final letters.
The final letter of 'drop' is 'p'.
'li'+'s'+'p'='LISP'

Can you help me to learn more?

(Other definitions for lisp that I've seen before include "Speak with defective sibilants" , "Talk like thith" , "Non-standard pronunciation" , "peech impediment" , "Slip into speech defect" .)

I've seen this clue in The Hindu.

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