Likewise or similarly in other lexica; references at Photius pi833, where Theodoridis declares the source of the headword -- perfect indicative, third person singular, of fenaki/zw -- to be Demosthenes 2.7 (pefena/kik' there). In fact there are two other alternatives in Demosthenes: 19.72 (pefena/kike) and 23.162 (pefena/kiken).
For the verb itself see phi 196 (and cf. phi 194, phi 195).