Can anyone recommend any agency to help Ghanaians gain a work permit?

Please go through the below link, create your profile and start applying jobs which are very much matching to your profile. It’s not easy to get a job here but there is nothing wrong to try.

No agency can help you on this. Start reading posts which have many information can help you to understand the job market here. Good luck

https://www.expat.com/forum/viewtopic.php?id=804667

A Singapore "Work Permit" or WP (which is one kind of several work visa available) is normally only issued to candidates from a number of (Asian) source countries. I do not think you, as a Ghanaian, have a chance here.
If however, you meant it generally as "any kind of work visa": You may be eligible for one of the other kinds, which are S-Pass and Employment Pass (EP) if you fulfill the criteria (i.e. university degree or technical certificate, or equivalent, plus applicable work experience) and find a job at a suitable employer.
Job agencies are generally useless (only take fees and may even scam you). It is better to avoid them and apply for jobs directly.

Thank you so much 🙏🏾