also: いちにかかって
depends entirely on; hinges on
Used to emphasize that the outcome or success of something is completely determined by a single factor. Often followed by ～かどうか or a noun phrase.
Whether we succeed or not depends entirely on your effort.
Whether he passes depends entirely on the final interview.
Standard kanji-kana mixed spelling for the reading ひとつにかかって.
Alternate spelling with the reading いちにかかって. Less common than 一つにかかって.
Variant using the kanji 掛 for かかって. Slightly more formal or emphatic.
Rare variant combining the 一 spelling with 掛. Mostly seen in older texts.
From 一つ (one thing) + に (particle) + かかって (te-form of かかる, 'to depend on'). Literally 'hanging on one thing', it became a set phrase meaning 'depends entirely on'.