Some idiots ignore meaningful gesture (4)
I believe the answer is:
sign
'gesture' is the definition.
(sign is a kind of gesture)
'some idiots ignore meaningful' is the wordplay.
'some' indicates the answer is hidden within the clue (some of the parts of the word are used).
'SIGN' can be found hidden inside 'idiots ignore meaningful'.
(Other definitions for sign that I've seen before include "Indication - put one's name down" , "house" , "Indicator" , "Public display of a message" , "Public notice; gesture" .)