Bound reading limited to two niches. Old/literary: artisan workshop, as in 作坊. Modern internet slang: a verb for 'asking for trouble' or 'being a drama queen' - heavy in northern speech and dating-talk (作死, 她真作). Don't confuse with the primary 作 reading.
memory
The slang sense rhymes with the workshop sense - a 作 person 'manufactures' drama the way an artisan manufactures goods. Both readings share the idea of effortful production rather than the broad 'do' of 作.
Left person radical - side-form of 人. The indexing radical (Kangxi #9). Doing, making, working are all things people perform, so the human focus is literal. Same radical heads 你, 他, 们, 住, 修 - the bulk of person-related vocab and human-action verbs.
Right component supplies the sound (zhà → zuò, a regular old-Chinese palatal-to-affricate drift). 乍 itself originally pictured a knife cutting a sleeve, the act of starting work on a garment, which is sometimes read as a faint semantic echo of 'beginning a task'. Same phonetic in 昨 (yesterday), 怎 (how), 炸 (explode), 窄 (narrow).
