Conservative, forty-nine maybe? (6)

I believe the answer is:

square

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'conservative' is the definition.
(I know that square is a type of conservative)

I cannot understand how the remainder of the clue works.

Can you help me to learn more?

(Other definitions for square that I've seen before include "uncool" , "quits" , "Centre of cricket ground" , "Figure with four equal sides" , "Bribe" .)

I've seen this clue in The Telegraph.

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