... faithful left king, maybe, dropping leader (5)
I believe the answer is:
loyal
'faithful' is the definition.
('loyal' can be similar in meaning to 'faithful')
'left king maybe dropping leader' is the wordplay.
'left' becomes 'l' (common abbreviation).
'king maybe' becomes 'royal'.
'dropping leader' means to remove the first letter.
'royal' with its first letter removed is 'oyal'.
'l'+'oyal'='LOYAL'
(Other definitions for loyal that I've seen before include "Alloy (anag.)" , "firm in solidarity" , "Dependable" , "True-hearted" , "Steadfast and true" .)