Firstly are you sure you mean "Water Inlet". Washing machines have
dedicated fill hoses which do not use jubilee clips. I presume you mean
the waste outlet or DRAIN HOSE.

A jubilee clip will come into play in this scenario to attach the drain
hose to a drain spigot (hole) in the waste trap under the kitchen sink.
Usually if there is no drain hose attached to the waste trap then water
will p*ss out under the sink when the tap is run.

Assuming we are talking about the waste outlet, you shouldn't have to
unscrew the jubilee clip at all because you should just be able to slip
it over the end of the drain hose, push the hose onto the corresponding
drain spigot under the kitchen sink, and then tighten it up. From new,
Jubilee clips are fully undone. Perhaps you have got the wrong size.
From memory you probably want about a 30mm diameter Jubilee clip. If in
doubt measure the diameter of the drain hose and take it from there -
get a jubilee clip about 5 mm bigger.

Hope this helps.