Can combinational variability manifest itself in the absence of a sexual process?

No. Combinational variability consists in the appearance of new traits as a result of the formation of other combinations of parental genes in the genotypes of descendants. The basis of this type of variability lies in the independent divergence of homologous chromosomes in the first meiotic division, the random encounter of gametes in the same parent pair during fertilization, and the random selection of parent pairs. It also leads to recombination of genetic material and increases the variability of the exchange of regions of homologous chromosomes that occurs in the first prophase of meiosis. Thus, in the process of combinational variation, the structure of genes and chromosomes does not change, however, new combinations of alleles lead to the formation of new genotypes and, as a result, the appearance of descendants with new phenotypes.