Pretend to have left note out (3,2)
I believe the answer is:
let on
'pretend' is the definition.
(thesaurus)
'left note out' is the wordplay.
'left' becomes 'l' (common abbreviation).
'out' indicates an anagram (out can mean wrong or inaccurate).
'note' anagrammed gives 'eton'.
'l'+'eton'='LET ON'
'to have' acts as a link.
(Other definitions for let on that I've seen before include "give the game away" , "Allow to board, or pretend" , "Spill the beans" , "Divulge (secret to)" , "Pretend informally or permit to board" .)