Doctor means I must go before a complaint (7)
I believe the answer is:
amnesia
'complaint' is the definition.
(medical complaint)
'doctor means i must go before a' is the wordplay.
'doctor' indicates an anagram.
'must go before' is a charade indicator (letters next to each other).
'means' with letters rearranged gives 'amnes'.
'amnes'+'i'+'a'='AMNESIA'
(Other definitions for amnesia that I've seen before include "Failure to recall" , "Mental condition" , "memory problem" , "Defect in memory" , "Partial or total loss of memory" .)