Can effect be applied to core code?

you must apply the css class to the image like this

<img src="/images/yourimage.jpg" class="effectck-lily" title="My title::A little description" />

so in your case it would be

just gave it a try, doesn't work

I added it like

$html .= '<div class="js-image">';
if($fieldsordering == 1 && $listjobconfig==1){
$html .= '<a href="'.$link_viewcomp.'"><img class="effectck-apollo" src="'.$path.'" title="'.$job->companyname.'"></a>';
}

it works
the problem is the interaction with other css
line 684 in your style.css file on

div#js-jobs-wrapper div.js-toprow div.js-image a img

you have some css to remove

then the second problem is that there is a link positioned in absolute over the image, once you hover it, you are not hovering the image for the effect, but the link !
in fact you don't see the effect

all this is due to the structure of your component, I would suggest to remove the css classes that are in conflict because you can not use the html structure and position of the component, and use image effect in the same time (image effect does not affect the image position )

but i would still be able to see the images yes? there are no images now to be seen?

no, I'm trying to explain that the css coming from the component :
alexanderrhodes.co.uk/Fresh/components/com_jsjobs/css/style.css
are positioning the elements differently, it moves the image out of the visual area with an absolute position

here it is a custom request to adapt the code, this is no in my scope ...
you would need to rethink the html and css code of the component to put all elements in a normal behavior again