Gentleman eats the last piece of éclair before cheese is served (7)

I believe the answer is:

gruyere

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'cheese is served' is the definition.
I can't tell whether this defines the answer.

'gentleman eats the last piece of eclair before' is the wordplay.
'gentleman' becomes 'guy' (I can't justify this - if you can you should believe this answer much more).
'eats' is an insertion indicator.
'the last piece of' suggests the final letters.
'before' becomes 'ere' (poetic term for 'before').
The final letter of 'eclair' is 'r'.
'guy' enclosing 'r' is 'gruy'.
'gruy'+'ere'='GRUYERE'

Can you help me to learn more?

(Other definitions for gruyere that I've seen before include "Firm Swiss cheese" , "Swiss holes surrounded by cheese!" , "Swiss cheese with small holes" , "Type of Swiss cheese" , "Whole-milk Swiss cheese" .)

I've seen this clue in The Independent.

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