Girl in church picked up stringed instrument (6)
I believe the answer is:
cheryl
'girl' is the definition.
'church picked up stringed instrument' is the wordplay.
'church' becomes 'ch' (common abbreviation).
'picked up' says the letters should be written in reverse.
'stringed instrument' becomes 'lyre' (lyre is a kind of stringed instrument).
'lyre' written backwards gives 'eryl'.
'ch'+'eryl'='CHERYL'
'in' acts as a link.
(Other definitions for cheryl that I've seen before include "Woman" , "- Studer, US soprano" , "Girl" .)