Best titfer? (3,3)

I believe the answer is:

top hat

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'best titfer?' is the definition.
The definition suggests a singular noun which matches the answer.

'best titfer?' is the wordplay.
'best' becomes 'top' (top can mean the very best).
'titfer?' becomes 'hat' (I can't justify this - if you can you should give a lot more credence to this answer).
'top'+'hat'='TOP-HAT'

Can you help me to learn more?

(Other definitions for top hat that I've seen before include "Posh lid" , "Formal head covering" , "Formal attire" , "Headgear (for those in tails?)" , "Man's cylindrical headgear" .)

I've seen this clue in the Evening Standard.

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