Devoted, faithful (5)
I believe the answer is:
loyal
I believe this clue is a double definition.
'devoted' is the first definition.
(similar in meaning)
'faithful' is the second definition.
(similar in meaning)
(Other definitions for loyal that I've seen before include "Dependable" , "Trustworthy" , "one can trust" , "Dedicated" , "Steadfast in allegiance" .)