Being unable to recall a name is troublesome (7)
I believe the answer is:
amnesia
'being unable to recall' is the definition.
I can't judge whether this definition defines the answer.
'a name is troublesome' is the wordplay.
'troublesome' indicates anagramming the letters.
'name'+'is'='nameis'
'nameis' with letters rearranged gives 'mnesia'.
'a'+'mnesia'='AMNESIA'
Can you help me to learn more?
(Other definitions for amnesia that I've seen before include "Elephants won't suffer such" , "Partial or total loss of memory" , "illness" , "Seaman I find suffering from memory loss" , "Severe forgetfulness" .)