Ruth to be mine before year (4)
I believe the answer is:
pity
'ruth' is the definition.
('pity' can be a synonym of 'ruth')
'mine before year' is the wordplay.
'mine' becomes 'pit' (down the pit).
'before' means one lot of letters go next to another.
'year' becomes 'y'.
'pit'+'y'='PITY'
'to be' acts as a link.
(Other definitions for pity that I've seen before include "Matter for regret" , "Cause for regret" , "Feel sorrow for" , "Commiseration" , "Sympathy for others" .)