Choose the best carbon content for steel, possibly (6)
I believe the answer is:
select
'choose' is the definition.
(I know that choose can be written as select)
'best carbon content for steel possibly' is the wordplay.
'best' becomes 'sele' (I can't justify this - if you can you should believe this answer much more).
'carbon' becomes 'C' (C is the chemical symbol for carbon).
'content for' says to take the centre.
'steel possibly' becomes 'metal' (steel is a metal).
The central letter of 'metal' is 't'.
'sele'+'c'+'t'='SELECT'
'the' is the link.
Can you help me to learn more?
(Other definitions for select that I've seen before include "Appoint" , "'Choose, pick out (6)'" , "Choice, picked out" , "Carefully chosen; choose" , "Choose, decide" .)