More primitive serial killer lacks criminal skill (7)

I believe the answer is:

earlier

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'more primitive' is the definition.
('early' can be similar in meaning to 'primitive')

I don't understand the rest of the clue.

Can you help me to learn more?

(Other definitions for earlier that I've seen before include "Sooner in time" , "Rare lie (anag)" , "Further in advance" , "Formerly" , "in days of yore?" .)

I've seen this clue in The Irish Times.

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