Many compositions in written form (6)
I believe the answer is:
scores
This clue could be a double definition.
'many' is the first definition.
(thesaurus)
'compositions in written form' is the second definition.
'scores' can be an answer for 'compositions' (score is a kind of composition). I am not sure about the 'in written form' bit.
Can you help me to learn more?
(Other definitions for scores that I've seen before include "Puts ball in the net" , "Obtains marks, say" , "Gains game points" , "Written forms of musical compositions" , "Records" .)