Live without diamonds, comfortably (4)
I believe the answer is:
well
'comfortably' is the definition.
('well' can be a synonym of 'comfortably')
'live without diamonds' is the wordplay.
'live' becomes 'dwell' ('dwell' can be a synonym of 'live').
'without' indicates named letters should be taken away.
'diamonds' becomes 'd' (abbreviation in bridge say).
'dwell' with 'd' taken out is 'WELL'.
(Other definitions for well that I've seen before include "Healthy - water supply" , "Pour - thoroughly" , "Spring - in good health" , "Flood - thoroughly" , "Facial hair" .)