Some careless language? (5)
I believe the answer is:
'some careless language?' is the definition.
'slang' can be an answer for 'language?' (slang is a kind of language). I am unsure of the 'some careless' bit.
'some careless language?' is the wordplay.
'some' indicates the answer is hidden within the clue (some of the parts of the word are used).
'SLANG' is hidden in the letters of 'careless language'.
Can you help me to learn more?
(Other definitions for slang that I've seen before include "colloquialisms" , "type of language?" , "... to scold" , "Informal speech" , "Informal language used by a set of people" .)