Dreary old poet takes turn (4)
I believe the answer is:
drab
'dreary' is the definition.
(I know that dreary can be written as drab)
'old poet takes turn' is the wordplay.
'old poet' becomes 'bard' (I've seen this before).
'takes turn' shows that the letters should be reversed in order (I've seen 'taking turn' mean this).
'bard' in reverse letter order is 'DRAB'.
(Other definitions for drab that I've seen before include "woman with slatternly habits" , "Colourless like bard" , "Dowdy" , "Of a dull greenish-brown colour" , "Dingy, dull" .)