Extensive notes showing how much policemen are indebted? (7)
I believe the answer is:
copious
'extensive' is the definition.
(synonyms)
'much policemen are indebted?' is the wordplay.
'much' means to remove the last letter (much but not all of the word).
'policemen' becomes 'cops' (cop is a kind of policeman).
'are indebted?' becomes 'ious' (I can't justify this - if you can you should believe this answer much more).
'cops' with its last letter removed is 'cop'.
'cop'+'ious'='COPIOUS'
'notes showing how' acts as a link.
I am not very happy about this link. Some or all of it may belong to another bit of the clue.
(Other definitions for copious that I've seen before include "Many" , "Abundant in supply" , "Plentiful, existing in large amounts" , "Ample" , "abundance" .)