Was unaware of processing pelts (5)

I believe the answer is:

slept

I'm a little stuck... Click here to teach me more about this clue!

'was unaware' is the definition.
I can't judge whether this definition defines the answer.

'processing pelts' is the wordplay.
'processing' is an anagram indicator.
'pelts' anagrammed gives 'SLEPT'.

'of' is the link.

Can you help me to learn more?

(Other definitions for slept that I've seen before include "Slumbered" , "Had room for" , "Was dormant" , "Napped, dozed" , "Snoozed" .)

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