Having recovered from again (4)
I believe the answer is:
over
'again' is the definition.
(as in the phrases 'start over' and 'start again')
'having recovered from' is the wordplay.
'from' says the answer is hidden in the clue.
'OVER' is hidden in the letters of 'having recovered'.
(Other definitions for over that I've seen before include "Invalidate - upset" , "bridge?" , "Period of play" , "Bout of six bowls in cricket" , "Excessive" .)