Stupidity of ten caught in awful DIY (6)
I believe the answer is:
idiocy
'stupidity' is the definition.
(idiocy is a kind of stupidity)
'ten caught in awful diy' is the wordplay.
'ten' becomes 'io' (IO resembles 10).
'caught' becomes 'c' (cricket abbreviation).
'in' indicates putting letters inside.
'awful' indicates anagramming the letters.
'io'+'c'='ioc'
'diy' anagrammed gives 'idy'.
'ioc' placed inside 'idy' is 'IDIOCY'.
'of' acts as a link.
(Other definitions for idiocy that I've seen before include "Inanity" , "Foolish action or behaviour" , "Stupid behaviour or talk" , "Extreme foolishness" , "Chopper" .)