Perhaps armour's forte (6,4)

I believe the answer is:
strong suit
'forte' is the definition.
(I've seen this in another clue)
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for strong suit that I've seen before include "Something at which one excels" , "special talent" .)
I've seen this clue in The Guardian.
Want a hint initially instead of a full solution?
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