Coffer's empty often on a small farm (5)
I believe the answer is:
croft
'a small farm' is the definition.
(Scottish term for a small farm)
'coffer's empty often on' is the wordplay.
'empty' means to remove the middle letters.
'often' becomes 'oft' (synonyms).
'on' says to put letters next to each other.
'coffer' with its middle taken out is 'cr'.
'cr'+'oft'='CROFT'
(Other definitions for croft that I've seen before include "Plot" , "Farm up north" , "Small Scottish rented farm" , "Small (Scots) farm" , "Scottish farmstead" .)