Indication in slang isn't taken the wrong way (6)
I believe the answer is:
signal
'indication' is the definition.
(I know that indication can be written as signal)
'in slang isn't taken the wrong way' is the wordplay.
'in' indicates a hidden word.
'taken the wrong way' says the letters should be written in reverse.
'langis' is hidden in the letters of 'slang isnt'.
'langis' written backwards gives 'SIGNAL'.
(Other definitions for signal that I've seen before include "Gesture encoding a message" , "Communication by sign" , "way to communicate" , "Silent communication" , "Gesture of communication" .)