Short drink relative knocked back, little one (7)

I believe the answer is:

toddler

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

'short drink relative knocked back' is the wordplay.
'short drink' becomes 'todd' (I can't explain this - if you can you should believe this answer much more).
'relative' becomes 'rel' (mathematical abbreviation).
'knocked back' shows that the letters should be reversed in order.
'rel' in reverse letter order is 'ler'.
'todd'+'ler'='TODDLER'

Can you help me to learn more?

(Other definitions for toddler that I've seen before include "Lord Ted (anag)" , "Feeble walker" , "Child just walking" , "Little one" , "Young walker" .)

I've seen this clue in The Times.

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