Changeable writer to stop going through dictionary (4-5)
I believe the answer is:
open-ended
'changeable' is the definition.
(similar in meaning)
'writer to stop going through dictionary' is the wordplay.
'writer' becomes 'pen' (something which writes).
'to stop going' becomes 'end' (end can mean to stop).
'through' is an insertion indicator (inserted letters go through the word).
'dictionary' becomes 'OED' (Oxford English Dictionary).
'pen'+'end'='penend'
'penend' placed into 'oed' is 'OPEN-ENDED'.
(Other definitions for open-ended that I've seen before include "Allowing free debate with no set time to finish." , "Without fixed limits or restrictions" , "With no fixed limit, not circumscribed" , "Having no predetermined limit" , "Having no fixed limit, perhaps a discussion" .)