In certain ways, a piece of metal can turn up corroded (5)
I believe the answer is:
eaten
'corroded' is the definition.
(I've seen this in another clue)
'in certain ways a piece' is the wordplay.
'in' means one lot of letters goes inside another.
'certain ways' becomes 'ete' (I can't explain this - if you can you should give a lot more credence to this answer).
'piece' becomes 'n' (abbreviation for Knight in chess notation).
'ete' enclosing 'a' is 'eate'.
'eate'+'n'='EATEN'
'of metal can turn up' is the link.
This may not be correct. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for eaten that I've seen before include "Scoffed" , "Put away" , "dinners should be" , "Consumed" , "dined" .)