Lewis & Short

suc-cĭno (subc-; also succăno, Varr. L. L. 6, § 75 Müll.), ĕre, v. a. and n. [cano], to sing to, accompany (rare).

  1. I. Lit.: tubicines imitatus est succinente Habinnā, Petr. 69, 4: cantibus iste tuis alterno succinet ore, Calp. Ecl. 4, 79.
  2. II. Transf., to accord, agree: (agricultura) succinit pastorali, Varr. R. R. 1, 2, 16: clamat: Victum date. Succinit alter: Et mihi, etc., another chimes in, Hor. Ep. 1, 17, 48.