It's dismal in poetry putting attention on darker edges (5)
I believe the answer is:
drear
'it's dismal in poetry' is the definition.
(I've seen this in another clue)
'attention on darker edges' is the wordplay.
'attention' becomes 'ear' (having someone's ear is having their attention).
'on' means one lot of letters go next to another.
'edges' means to remove the middle letters (I've seen 'edges of' mean this).
'darker' with its middle taken out is 'dr'.
'ear' after 'dr' is 'DREAR'.
'putting' is the link.
(Other definitions for drear that I've seen before include "Cheerless (literary)" , "Depressingly dull" , "Dull and tedious" , "gloomy in poem" , "Literarily gloomy" .)