How is the electronegativity trend related to the first ionization energy trend?

The greater the electronegativity the greater the first ionization energy. An increase in ionization energy led to an increase in the ionization energy. Electronegativity is the attract electron while ionization energy is energy required to remove electron and hence if an atom has great electronegativity it cannot loss an electron easily

Electronegativity is the tendency of an atom to attract electrons ... The greater the affinity for electrons, the greater the ionization energy needed for electron removal. So atoms with greater electronegativities also have greater ionization energies, and their trends follow the same pattern on the periodic table.