Try to break into painting's special language (5)
I believe the answer is:
argot
'special language' is the definition.
(I've seen this before)
'try to break into painting's' is the wordplay.
'try' becomes 'go' (both can mean an attempt).
'to break into' indicates putting letters inside (inserted letters break into the word).
'painting' becomes 'art' (painting is an art).
'go' inserted within 'art' is 'ARGOT'.
(Other definitions for argot that I've seen before include "secret language" , "Patois, vernacular" , "Slang for a groat (5)" , "Patois for groat" , "Father or mother" .)