William somewhat poorly (3)
I believe the answer is:
ill
'poorly' is the definition.
(I know that poorly can be written as ill)
'william somewhat' is the wordplay.
'somewhat' indicates the answer is hidden within the clue.
'ILL' is hidden in the letters of 'william'.
(Other definitions for ill that I've seen before include "In bad health" , "laid up?" , "US state" , "Badly diminished" , "Valetudinarian" .)