Hard to fathom the more primitive part of life (11)

I believe the answer is:

bewildering

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'hard to fathom' is the definition.
I can't tell whether this definition defines the answer.

'more primitive part of life' is the wordplay.
'more primitive' becomes 'wilder' (I've seen this before).
'part of' means one lot of letters goes inside another (part of the inside).
'life' becomes 'being' (I can't justify this - if you can you should believe this answer much more).
'wilder' put inside 'being' is 'BEWILDERING'.

'the' acts as a link.

Can you help me to learn more?

(Other definitions for bewildering that I've seen before include "complex" , "Baffling" , "Perplexing" , "enigmatic" , "Amazing" .)

I've seen this clue in The Irish Times.

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