Element concealed by faithful friend, devoted (6)
I believe the answer is:
doting
'devoted' is the definition.
(I've seen this before)
'element concealed by faithful friend' is the wordplay.
'element' becomes 'tin' (tin is a kind of element).
'concealed by' indicates putting letters inside.
'faithful friend' becomes 'dog' (a dog is man's best friend).
'tin' put inside 'dog' is 'DOTING'.
(Other definitions for doting that I've seen before include "Excessively fond" , "Uncritically fond" , "Overly fond of, say spouse" , "Showing excessive love" , "Showing great fondness as for a spouse" .)