be in (too) deepto be very involved in a situation, especially so that it causes you problems
[TahlilGaran] Dictionary of Contemporary English ▲
in deep adj. phr. Seriously mixed up in something, especially trouble.
George began borrowing small sums of money to bet on horses, and before he knew it he was in deep. Compare: DEEP WATER, UP TO THE CHIN IN.
[TahlilGaran] English Idioms Dictionary ▲