No elm can provide the answer (5)
I believe the answer is:
lemon
'the answer' is the definition.
(I have seen 'Unhelpful answer' mean 'lemon' so perhaps 'answer' could also mean 'lemon')
'no elm can' is the wordplay.
'can' indicates anagramming the letters (I've seen 'canned' mean this (canned can mean drunk)).
'no'+'elm'='noelm'
'noelm' anagrammed gives 'LEMON'.
'provide' acts as a link.
(Other definitions for lemon that I've seen before include "something defective" , "Melon is another fruit" , "Washout" , "Defective object" , "leaving bitter taste?" .)