Quietly, girl changed idea for journey (10)
I believe the answer is:
pilgrimage
'for journey' is the definition.
(pilgrimage is a kind of journey)
'quietly girl changed idea' is the wordplay.
'quietly' becomes 'p' (musical symbol).
'changed' indicates anagramming the letters.
'idea' becomes 'image' (I've seen this in another clue).
'girl' is an anagram of 'ilgr'.
'p'+'ilgr'+'image'='PILGRIMAGE'
(Other definitions for pilgrimage that I've seen before include "Religiously inspired journey" , "What Chaucer,s travellers were engaged upon" , "journey to shrine" , "Journey to a sacred place" , "Holy journey" .)