Taking up little space in the agreement (7)
I believe the answer is:
compact
'taking up little' is the definition.
'compact' can be an answer for 'little' (I've seen this before). I'm unsure of the 'taking up' bit.
'space in the agreement' is the wordplay.
'space in' becomes 'com' (I can't justify this - if you can you should give a lot more credence to this answer).
'the agreement' becomes 'pact' (a pact is an agreement or deal).
'com'+'pact'='COMPACT'
Can you help me to learn more?
(Other definitions for compact that I've seen before include "Agreement - brief" , "Concise" , "bargain" , "Small case for face-powder" , "An official agreement" .)