Frank to make pretence of strength (5)

I believe the answer is:

bluff

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'frank' is the definition.
(synonyms)

I don't understand the rest of the clue.

(Other definitions for bluff that I've seen before include "Rocky outcrop" , "Challengers may call it" , "Deception - hearty" , "Mislead; cliff; hearty" , "What a poker player does - or tries to" .)

I've seen this clue in The Irish Independent.

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