Rubbish in statistics (3)
I believe the answer is:
tat
'rubbish' is the definition.
(tat can mean rubbish or poor-quality material)
'in statistics' is the wordplay.
'in' indicates the answer is hidden within the clue.
'TAT' can be found hidden inside 'statistics'.
(Other definitions for tat that I've seen before include "Inferior articles" , "Tawdry and shabby article" , "Worthless items" , "Shoddy articles" , "Utterly tasteless objects" .)