Alloy turns out to be dependable (5)
I believe the answer is:
loyal
'be dependable' is the definition.
(I've seen this before)
'alloy turns out' is the wordplay.
'turns out' indicates anagramming the letters.
'alloy' anagrammed gives 'LOYAL'.
'to' is the link.
(Other definitions for loyal that I've seen before include "Faithful - true" , "Faithful to country, cause or friend" , "Trusty" , "Steadfast in allegiance" , "Faithful - reliable" .)