Son lost out on diamonds - that happens twice a year (8)
I believe the answer is:
solstice
'son lost out on diamonds that happens twice a year' is the definition.
Although both the answer and definition are singular nouns, I cannot understand how one could define the other.
'son lost out on diamonds' is the wordplay.
'son' becomes 's' (genealogical abbreviation for son).
'out' indicates anagramming the letters (out can mean wrong or inaccurate).
'on' indicates putting letters inside (as in clothing 'on' a person).
'diamonds' becomes 'ice' (slang term for diamonds).
'lost' is an anagram of 'olst'.
's' inserted into 'olst' is 'solst'.
'solst'+'ice'='SOLSTICE'
Can you help me to learn more?
(Other definitions for solstice that I've seen before include "Closest I come to time when sun is farthest from equator" , "Shortest or longest day of the year" , "Time of year when sun is furthest from equator" , "When night and day are most unequal" , "21 June or 22 December?" .)