Apretar (Spanish for “to squeeze”) comes from the Latin pectus, meaning, “chest.” Think of having a heart attack: your chest feels squeezed. It’s not a coincidence that doctors in the USA today still call a heart attack, angina pectoris — that is, “angina of the chest” since pectoral in English today still means “relating to the chest”! The p‑t maps to the p‑ct, with the ‑ct- just simplifying into its first ‑c- sound.
Related: see also Pecho/Pectoral. From the same pectus root, we see other interesting words, following the ch/ct pattern.