One's strong suit or forte (6)
I believe the answer is:
metier
I believe this clue is a double definition.
'one's strong suit' is the first definition.
(I've seen this before)
'forte' is the second definition.
(I know that forte can be written as metier)
(Other definitions for metier that I've seen before include "One's trade, art or calling" , "job" , "Profession, occupation" , "One's strong point" , "That at which one excels, one's forte" .)