Mood of soft stringed instrument reflected a new church (9)
I believe the answer is:
petulance
'mood' is the definition.
(petulance is a kind of mood)
'soft stringed instrument reflected a new church' is the wordplay.
'soft' becomes 'p' (musical abbreviation for 'piano', soft).
'stringed instrument' becomes 'lute' (lute is a type of stringed instrument).
'reflected' is a reversal indicator (letters reflected back).
'new' becomes 'n' (abbreviation as in New Testament NT).
'church' becomes 'ce' (abbreviation for Church of England).
'lute' backwards is 'etul'.
'p'+'etul'+'a'+'n'+'ce'='PETULANCE'
'of' acts as a link.
(Other definitions for petulance that I've seen before include "ill humour" , "Childish sulkiness" , "Childish bad-temper" , "Peevishness" , "Peevish irritation" .)