I'm assuming you've carried out ozonolysis followed by mild reduction (e.g. using $\ce{Me2S}$) to generate a dialdehyde and now want to convert it to a monoaldehyde. Wolff-Kishner requires basic conditions, so you need a PG insensitive to base. Using ethylene glycol (1 equiv.) in mild acid over a dehydrating agent to generate an acetal would do, but you would need to optimise the conditions to ensure that only one of the aldehyde groups reacts. Then you can carry out Wolff-Kishner as usual and, finally, release the aldehyde in mild acid and excess water.
The question is why would you ever need to do that, if the resulting n-hexanal is readily available from most chemical suppliers?