  Stellar theory enables us to understand the properties of stars at different
stages of their evolution, and contributes to other fields of astrophysics such
as galactic and exoplanet studies. Assessing the accuracy of stellar theories
necessitates high precision, model-independent measurements of the properties
of real stars, such as those obtainable for the components of double lined
eclipsing binaries (DLEBs), while asteroseismology offers probing power of the
stellar interior if one or both components pulsate. KIC 4851217 is a DLEB
containing two late A-type stars and exhibits pulsations of the $\delta$ Scuti
type. By analysing high resolution HERMES and moderate resolution ISIS spectra,
jointly with Kepler and TESS light curves, we measured the masses, radii and
effective temperatures of the components to precisions of ~0.5, ~1.1 and ~1 per
cent, respectively. We additionally report the discovery and characterisation
of a tertiary M-dwarf companion. Models of the system's spectral energy
distribution agree with an age of 0.82 Gyr, with the more massive and larger
secondary component near the end of the main sequence lifetime. An examination
of the pulsating component's pulsation frequencies reveals 39 pulsation
multiplets that are split by the orbital frequency. For most of these, it is
evident that the pulsation axes have been tilted into the orbital plane. This
makes KIC 4851217 a tidally tilted pulsator (TTP). This precisely characterized
$\delta$ Scuti DLEB is an ideal candidate for advancing intermediate-mass
stellar theory, contributing to our understanding of hierarchichal systems as
well as to the topic of TTPs.
