A predpossessive clause is a °clause in which an °indefinite nominal is said to be °possessed by a °definite possessor expression.
An example is 'My sister has a house.' A more traditional term is "predicative possession" (e.g. Stassen 2009), shortened here to "predpossessive" (cf. Haspelmath 2017: 196). ❡
It should be noted that predpossessive constructions are not "predicational" in that they lack a topic-comment structure, so the term is not particularly transparent. ("Predicative possession" was introduced in order to contrast with "attributive/adnominal possession", but "clausal possession" would probably have been a better choice.)