Statement not binding: I say (7)
I believe the answer is:
pronoun
'i say' is the definition.
(I've seen this before)
'statement not binding' is the wordplay.
'statement' becomes 'pro' (pro is a kind of statement).
'not binding' becomes 'noun' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'pro'+'noun'='PRONOUN'
Can you help me to learn more?
(Other definitions for pronoun that I've seen before include "He is one" , "Part of speech" , "Possibly he" , "Word like I or she" , "Substitute for a noun" .)