Minimum iron on bearing (6)
I believe the answer is:
fewest
'bearing' is the definition.
Both the definition and answer are adjectives. Maybe there's a link between them I don't understand?
'minimum iron on' is the wordplay.
'minimum' becomes 'west' (I can't justify this - if you can you should believe this answer much more).
'iron' becomes 'fe' (Fe is the chemical symbol for iron).
'on' is a charade indicator (letters next to each other).
'west' put after 'fe' is 'FEWEST'.
Can you help me to learn more?
(Other definitions for fewest that I've seen before include "Least abundant" , "most opposite" , "Minimum number" , "Lowest figure" , "The lowest number" .)