Glib irony with writer (4)
I believe the answer is:
biro
'writer' is the definition.
(type of pen, something which writes)
'glib irony with' is the wordplay.
'with' says the answer is hidden in the clue.
'BIRO' can be found hidden inside 'glib irony'.
(Other definitions for biro that I've seen before include "Writing implement" , "writer" , "Pocket item" , "Laszlo Jozsef -, ballpoint pen inventor" , "Type of ballpoint pen" .)