Proposal taken up, impresses strongman (5)

I believe the answer is:

atlas

I'm a little stuck... Click here to teach me more about this clue!

'up impresses strongman' is the definition.
The definition suggests a singular noun which matches the answer.

'proposal taken' is the wordplay.
'ATLAS' is hidden back-to-front in amongst the letters.
However, I'm unsure how the hidden word is indicated.

Can you help me to learn more?

(Other definitions for atlas that I've seen before include "Album of maps" , "Its architectural name is telamon" , "Asian satin" , "Geographical book" , "used for maps" .)

I've seen this clue in The Irish Times.

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