Am I sane, sadly forgetting things? (7)
I believe the answer is:
amnesia
'forgetting things?' is the definition.
(memory loss condition)
'am i sane sadly' is the wordplay.
'sadly' indicates an anagram.
'i'+'sane'='isane'
'isane' with letters rearranged gives 'nesia'.
'am'+'nesia'='AMNESIA'
(Other definitions for amnesia that I've seen before include "Inability to remember" , "Completely forgetting" , "Seaman I find suffering from memory loss" , "Memory-loss" , "Mental condition" .)