Exclude some testimony that's been retracted (4)
I believe the answer is:
omit
'exclude' is the definition.
(I know that exclude can be written as omit)
'some testimony that's been retracted' is the wordplay.
'some' says the answer is hidden in the clue (some of the parts of the word are used).
'that's been retracted' shows that the letters should be reversed in order.
'timo' can be found hidden inside 'testimony'.
'timo' reversed gives 'OMIT'.
(Other definitions for omit that I've seen before include "Disregard" , "Exclude; forget to include" , "Fail to include" , "Leave out or neglect" , "Don't include" .)