Brainless life-form a second president recalled? (6)

I believe the answer is:

amoeba

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'brainless life-form' is the definition.
I can't tell whether this defines the answer.

'a second president recalled?' is the wordplay.
'second' becomes 'mo' (both are short periods of time).
'president' becomes 'Abe' (Abraham (Abe) Lincoln).
'recalled?' is a reversal indicator (to recall can mean to bring something back).
'abe' backwards is 'eba'.
'a'+'mo'+'eba'='AMOEBA'

Can you help me to learn more?

(Other definitions for amoeba that I've seen before include "Protozoan life-form" , "Tiny organism consisting of single changing cell" , "Microscopic animal found in water" , "shape-shifter" , "Microscopic, single-cell creature" .)

I've seen this clue in The Sun.

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