Abandon urge to go after diamonds (5)
I believe the answer is:
ditch
'abandon' is the definition.
(ditching is a kind of abandoning)
'urge to go after diamonds' is the wordplay.
'urge' becomes 'itch' (I've seen this before).
'to go after' means one lot of letters go next to another.
'diamonds' becomes 'd' (abbreviation in bridge say).
'itch' after 'd' is 'DITCH'.
(Other definitions for ditch that I've seen before include "Type of trench" , "Land in water" , "drainage feature" , "Drainage channel" , "Drop" .)