  KIC 8560861 (HD 183648) is a marginally eccentric (e=0.05) eclipsing binary
with an orbital period of P_orb=31.973d, exhibiting mmag amplitude pulsations
on time scales of a few days. We present the results of the complex analysis of
high and medium-resolution spectroscopic data and Kepler Q0 -- Q16 long cadence
photometry. The iterative combination of spectral disentangling, atmospheric
analysis, radial velocity and eclipse timing variation studies, separation of
pulsational features of the light curve, and binary light curve analysis led to
the accurate determination of the fundamental stellar parameters. We found that
the binary is composed of two main sequence stars with an age of 0.9\+-0.2 Gyr,
having masses, radii and temperatures of M_1=1.93+-0.12 M_sun, R_1=3.30+-0.07
R_sun, T_eff1=7650+-100 K for the primary, and M_2=1.06+-0.08 M_sun,
R_2=1.11+-0.03 R_sun, T_eff2=6450+-100 K for the secondary. After subtracting
the binary model, we found three independent frequencies, two of which are
separated by twice the orbital frequency. We also found an enigmatic half
orbital period sinusoidal variation that we attribute to an anomalous
ellipsoidal effect. Both of these observations indicate that tidal effects are
strongly influencing the luminosity variations of HD 183648. The analysis of
the eclipse timing variations revealed both a parabolic trend, and apsidal
motion with a period of (P_apse)_obs=10,400+-3,000 y, which is three times
faster than what is theoretically expected. These findings might indicate the
presence of a distant, unseen companion.
