Turned sunward outside chapter house for early morning song (4,6)
I believe the answer is:
dawn chorus
'early morning song' is the definition.
'turned sunward outside chapter house' is the wordplay.
'turned' is an anagram indicator.
'outside' means one lot of letters goes inside another.
'chapter' becomes 'c'.
'house' becomes 'ho' (abbreviation for house).
'sunward' anagrammed gives 'dawnrus'.
'c'+'ho'='cho'
'dawnrus' enclosing 'cho' is 'DAWN CHORUS'.
'for' acts as a link.
(Other definitions for dawn chorus that I've seen before include "Birds singing at daybreak" , "Early sound of birds" , "Early morning sing-song?" , "Early bird song" , "singing, naturally" .)