Changes had to limit liquid measure — controlled quantities (11)

'changes' is the definition.
(I know this)

'had to limit liquid measure controlled quantities' is the wordplay.
'had' becomes 'ate' (e.g. I had an ice cream).
'to limit' means one lot of letters goes inside another.
'liquid measure' becomes 'L' (litre).
'controlled quantities' becomes 'rations' (rations are controlled amounts of something).
'ate' placed around 'l' is 'alte'.
'alte'+'rations'='ALTERATIONS'