Metal only covers part of claw (5)
I believe the answer is:
talon
'claw' is the definition.
(talon is a kind of claw)
'metal only covers part' is the wordplay.
'part' indicates the answer is hidden within the clue.
'TALON' is hidden in the letters of 'metal only covers'.
'of' is the link.
(Other definitions for talon that I've seen before include "hunting hook" , "One may be grabbing" , "Holding part of flier" , "a gripping one" , "Eg, an eagle's claw" .)