Writers putting Nightingale in Berkeley Square originally (4)
I believe the answer is:
nibs
'writers' is the definition.
(parts of pens, things which write)
'nightingale in berkeley square originally' is the wordplay.
'originally' suggests taking the first letters.
The initial letters of 'nightingale in berkeley square' is 'NIBS'.
'putting' is the link.
(Other definitions for nibs that I've seen before include "Writing tips of old pens" , "Pen tips" , "Crushed coffee/cocoa beans" , "Writing points" , "VIPs?" .)