Go through poetry being unreasonable (8)
I believe the answer is:
perverse
'unreasonable' is the definition.
(I've seen this before)
'go through poetry' is the wordplay.
'go through' becomes 'per' (I am not sure about this - if you are sure you should believe this answer much more).
'poetry' becomes 'verse' (synonyms).
'per'+'verse'='PERVERSE'
'being' is the link.
Can you help me to learn more?
(Other definitions for perverse that I've seen before include "Wrongly determined" , "Deviant" , "Cross-grained" , "'Contrary to what's considered right, proper or good (8)'" , "Preserve in order to be stubbornly intractable" .)