。
She was a bundle of jealousy.
Literal
She [topic-は] jealousy [genitive-の] lump [was-であった].
A literary, evocative metaphor: しっとのかたまり ('a lump/embodiment of jealousy') uses かたまり ('lump, clump, mass') in its figurative sense — the entirety of her was jealousy, packed into a single mass. The literary であった is the past form of the formal copula である, much weightier than だった; it lends a written, narrative tone often found in fiction or biography. かたまり (塊) is productive in similar metaphors — 善意のかたまり (a mass of goodwill), 才能のかたまり (talent personified), 矛盾のかたまり (a bundle of contradictions) — making this a stock rhetorical pattern for distilling a person down to a single defining quality.