It appears to be some orphan named Tom (7)

I believe the answer is:

phantom

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'it appears to' is the definition.
The definition suggests a singular noun which matches the answer.

'some orphan named tom' is the wordplay.
'some' says to take the centre.
'named' becomes 'an' (I can't explain this - if you can you should believe this answer much more).
The middle of 'orphan' is 'ph'.
'ph'+'an'+'tom'='PHANTOM'

'be' acts as a link.

Can you help me to learn more?

(Other definitions for phantom that I've seen before include "Illusion (at the opera?)" , "Sightseeing journey" , "Spirit" , "Something creepy" , "Ghost of the Opera" .)

I've seen this clue in the Evening Standard.

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