Reduced odd drip at small outhouse (10)
I believe the answer is:
diminished
'reduced' is the definition.
(similar in meaning)
'odd drip at small outhouse' is the wordplay.
'odd' indicates alternate letters.
'at' means one lot of letters go next to another.
'small' becomes 'mini' (I've seen this before).
'outhouse' becomes 'shed' (I've seen this before).
The alternating letters of 'drip' are 'di'.
'di'+'mini'+'shed'='DIMINISHED'
(Other definitions for diminished that I've seen before include "run down" , "weakened" , "Lessened" , "Not so impressive" , "Became less" .)