Believer is quiet and strangely hesitant (9)
I believe the answer is:
pantheist
'believer' is the definition.
(I know that pantheist is a type of believer)
'quiet and strangely hesitant' is the wordplay.
'quiet' becomes 'p' (music symbol for 'piano', ie soft or quiet).
'and' means one lot of letters go next to another.
'strangely' is an anagram indicator.
'hesitant' with letters rearranged gives 'antheist'.
'p'+'antheist'='PANTHEIST'
'is' is the link.
(Other definitions for pantheist that I've seen before include "everything one believes in?" , "Believer in many gods" , "Spinoza was one" , "Believer that god is in everything - even in Athens pit" .)