Component of arms that Iran bought in America originally (5)

I believe the answer is:

tibia

'component of arms' is the definition.
(the tibia is a bone of the arm)

'that iran bought in america originally' is the wordplay.
'originally' indicates taking the first letters.
The initial letters of 'that iran bought in america' is 'TIBIA'.

(Other definitions for tibia that I've seen before include "Part of leg of" , "ancient pipe" , "Bone in osso bucco" , "part of skeleton" , "Shin bone" .)

I've seen this clue in The Guardian.

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