To outward appearance, possibly ex-rental (8)

I believe the answer is:

external

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'to outward' is the definition.
(similar in meaning)

'appearance possibly ex-rental' is the wordplay.
'ex-rental' anagrams to 'EXTERNAL'.
However, I am unsure how the anagram is indicated.

Can you help me to learn more?

(Other definitions for external that I've seen before include "Relating to the outside" , "involving foreign nations" , "Surface" , "Belonging to the outside" , "Coming from outside" .)

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