The sentence 「ここでこなんことをしてられない！」comes from a book I'm reading. I have no idea where してられない comes from. My guess is that it's some colloquial potential form of する or something (there's a song named じっとしてられない), but I might be completely wrong. Can someone please help? Thank you in advance.
First of all, 「こなん」 should be 「こんな」 unless it is in a dialect I am unfamiliar with.
「してられない」 is the informal form of 「していられない」= "(I) can't be doing". So, it is the negative, potential and progressive form of 「する」.
In informal speech, the 「い」 is often dropped from phrases such as 「～ている」、「～ていた」, etc. Unless you are very new to the language, you must have encountered this phenomenon before.
The sentence, therefore, means:
"I can't be doing something like this here!"