Harmful creatures found in silver mine (6)
I believe the answer is:
vermin
'harmful creatures' is the definition.
(I've seen this before)
'in silver mine' is the wordplay.
'in' indicates a hidden word.
'VERMIN' is hidden within 'silver mine'.
'found' is the link.
(Other definitions for vermin that I've seen before include "Animals and birds of objectionable kind" , "Creatures troublesome to man" , "Odious creatures" , "Mice maybe" , "Small pests" .)