Old trainer in ring made of metal, iron (4-5)
I believe the answer is:
lion-tamer
'old trainer in ring' is the definition.
(animal trainer in a circus ring)
'of metal iron' is the wordplay.
'of' indicates anagramming the letters (the answer comes from or \'of\' the letters).
'metal'+'iron'='metaliron'
'metaliron' with letters rearranged gives 'LION-TAMER'.
'made' acts as a link.
(Other definitions for lion-tamer that I've seen before include "Circus performer" , "Circus entertainer" .)