Note that that Weblio "entry" is simply a messy generated thesaurus. Not much value.
I think I'll pull the plug on this and draft an entry for 隠し切れる/隠しきれる.

I think it should have an entry, like やりきれない, but I'm not 
adamant about it. There's also the dictionary entry for it

http://thesaurus.weblio.jp/content/隠し切
れない

See below.

I agree with the reality of that, but because one cannot realistically have an entry for every verb+ きれない, it does not mean that one cannot have an entry for the most predominantly used verbs+ きれない. Indeed, that does happen on the site. From the novice's point of view, there are two problems: (i) the question of searching [if one sees “隠しきれない” and searches for a meaning on the site, nothing comes up]; and (ii) if one realises one can search for “きれない” one gets the current entry, but it is a further step to add that description to “隠す” and get to the nuance intended. Of course, again I accept that once one has understood that coupling, then every verb+ きれない makes sense in context. If for practical purposes, you are opposed to gradually including entries for the predominantly used verbs+ きれない, then I wonder if you could expand the description of “きれない” by showing a few examples of predominantly used verbs+ きれない with the specific description for the combination. Finally, although the added sample sentences do help, it is often the case that picking out the specific description for the particular verb is not always as clear as the novice would need to understand.

Anyway, many thanks for giving this matter your consideration, which has prompted me to make this additional comment. As for me, personally, I have crossed the hurdle on this particular aspect so it is only your other users of the dictionary which are in focus; and I must accept that you have the experience and also that you must have the last word on these issues.

We can't have an entry for every_verb+きれない.  This is the reason that we have entries for suffixes.  I don't see a reason to single out 隠しきれない for inclusion.

See below.

I cannot help but agree to the observations about simplicity of the structure. However, the real issue is whether the simplicity of the structure, in the mind of the person who needs a dictionary, results in the understanding of the nuance intended by the user of the expression. Indeed, as with any language, the native speakers in general would understand the nuance of such expressions without even necessarily understanding the simplicity of the structure of the language. I may add, by way of compliment, that your dictionary demonstrates quite ably many examples where the true nuance of an expression could not have been understood by a novice who simply added A+B  together.