Record of two sides getting under twenty? (10)
I believe the answer is:
scoresheet
'record' is the definition.
'two sides getting under twenty?' is the wordplay.
'two sides' becomes 'sheet' (two sides of paper).
'getting under' says to put letters next to each other.
'twenty?' becomes 'score' ('score' can be a synonym of 'twenty').
'sheet' after 'score' is 'SCORESHEET'.
'of' acts as a link.
(Other definitions for scoresheet that I've seen before include "goal to get on this?" , "Record of players' performances" .)