Began to admit part in allowing free expressions of opinion (4-5)
I believe the answer is:
open-ended
'allowing free expressions of opinion' is the definition.
I can't tell whether this definition defines the answer.
'began to admit part' is the wordplay.
'began' becomes 'opened' (opening is a kind of beginning).
'to admit' means one lot of letters goes inside another.
'part' becomes 'end' (end is a kind of part).
'opened' enclosing 'end' is 'OPEN-ENDED'.
'in' is the link.
Can you help me to learn more?
(Other definitions for open-ended that I've seen before include "Having no fixed limit, perhaps a discussion" , "Without fixed limits or restrictions" , "Allowing free debate with no set time to finish." , "Having no predetermined limit" , "With no fixed limit, not circumscribed" .)