Faithful ally, excited to receive Oscar (5)
I believe the answer is:
loyal
'faithful' is the definition.
('loyal' can be similar in meaning to 'faithful')
'ally excited to receive oscar' is the wordplay.
'excited' indicates an anagram.
'to receive' indicates putting letters inside.
'oscar' becomes 'o' (phonetic alphabet: alpha, bravo, charlie etc.).
'ally' with letters rearranged gives 'lyal'.
'lyal' placed around 'o' is 'LOYAL'.
(Other definitions for loyal that I've seen before include "one can trust" , "Unwaveringly devoted to friend or cause" , "firm in solidarity" , "Alloy (anag.)" , "Dependable" .)