Long look at some simple error (4)
I believe the answer is:
leer
'long look' is the definition.
'leer' can be an answer for 'look' (leering is a kind of looking). I'm not certain of the 'long' bit.
'some simple error' is the wordplay.
'some' says the answer is hidden in the clue (some of the parts of the word are used).
'LEER' can be found hidden inside 'simple error'.
'at' is the link.
Can you help me to learn more?
(Other definitions for leer that I've seen before include "Look lasciviously at" , "Gaze lasciviously at" , "Lascivious gaze" , "unpleasant look" , "Suggestive or sneering look" .)