Ex-president saving man I’m not sure is more faithful (5)
I believe the answer is:
truer
'more faithful' is the definition.
('true' can be similar in meaning to 'faithful')
'ex-president saving man i'm not sure' is the wordplay.
'ex president' becomes 'tu' (I can't explain this - if you can you should believe this answer much more).
'saving' is an insertion indicator.
'man' becomes 'r' (abbreviation for rook, a chess piece or 'man').
'i'm not sure' becomes 'er' (expression of hesitation).
'tu' placed around 'r' is 'tru'.
'tru'+'er'='TRUER'
'is' acts as a link.
Can you help me to learn more?
(Other definitions for truer that I've seen before include "That's more like it" , "More real" , "More accurate" , "More faithful or straight" , "More in accordance with fact" .)