Nominally half the number on a tram (7)

I believe the answer is:

bertram

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'nominally half the number on a tram' is the definition.
I can't tell whether this defines the answer.

'half the number on a tram' is the wordplay.
'half the' means to take half the letters.
'on' says to put letters next to each other.
'number' halved is 'ber'.
'ber'+'tram'='BERTRAM'

Can you help me to learn more?

(Other definitions for bertram that I've seen before include "Wooster" , "Chap" .)

I've seen this clue in the Evening Standard.

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