I.e., in a contract. 'Intabulandi' is an objective genitive of the gerund or gerundive, with a substantive like 'memoranda' or 'memorandis' understood. A rare, but not unprecedented, construction in classical (including classic legal, e.g. Gaius') Latin.

'Clausulae' (not 'clausule', which is a Mediaeval barbarism) in this context seems to mean 'legal articles, clauses'. 'Intabulare' means literally 'to add onto the list/table', i.e., as one of the contractors.