Weakened (9)
'weakened' is the definition.
(similar in meaning)
This is all the clue.
(Other definitions for impaired that I've seen before include "hurt" , "Damaged, marred" , "Damaged or weakened, maybe in health" , "Spoilt" , "Injured; weakened" .)
'weakened' is the definition.
(thesaurus)
This is the entire clue.
(Other definitions for feeble that I've seen before include "Lacking strength or vigour" , "Weak or Fragile" , "Wimpish" , "Weak, debilitated" , "Paltry" .)
'weakened' is the definition.
(diluting is a kind of weakening)
This is all the clue.
(Other definitions for diluted that I've seen before include "Weaker" , "Lessened the strength of a solution" , "reduced in strength" , "Watered down or attenuated." .)
'weakened' is the definition.
(enervating is a kind of weakening)
This is the entire clue.
(Other definitions for enervated that I've seen before include "Weakened, spiritless" , "Deprived of vigour" , "Debilitated" .)
'weakened' is the definition.
(enfeebling is a kind of weakening)
This is the entire clue.
(Other definitions for enfeebled that I've seen before include "Weakened" , "Exhausted" .)