If I have the following:

eg.Manager
with a collection of Employees,
who each have a single ContactList property
which has a collection of PhoneNumbers
that have a Type property (work/home)

How do I query for all the work numbers for a particular manager's employees?

I'm not sure how to use the elements() function here, or where to join, and a pointer would be very much appreciated.

I believe the SQL would be like
SELECT p.*
FROM Managers m
LEFT OUTER JOIN Employees e on e.manager = m.id
LEFT OUTER JOIN PhoneNumbers p on p.contactlist = e.contactlist
WHERE p.type = 'work'

My actual working SQL is as follows, but I think the above is simpler to follow.

SELECT tn.formattedNumber
FROM Candidate c
LEFT OUTER JOIN CandidateProfileContactMethod cpcm on cpcm.candidate = c.id
LEFT OUTER JOIN ContactMethods cm on cm.id = cpcm.contactMethod
LEFT OUTER JOIN TelecomNumber tn on cm.telephone = tn.id
WHERE c.id =41 AND cm.telephone is not null;

In HQL it should look like:

I managed to get something working through trial and error, if it could be more efficient/better, let me know.

Here is my HQL query:

select cm from Candidate as c
left join c.candidateProfiles cp
left join cp.personalData.contactMethods.elements cm
where cm.telephone is not null and c.id = ?

Candidate has a List of CandidateProfile objects
each CandidateProfile has a PersonalData component
PersonalData has a List of ContactMethod objects
each ContactMethod has a Telephone object property

This query gets what I wanted, which is a list of all the Candidate's ContactMethods which contain a non-null Telephone

As it works, I am happy. If it could be better, I would be happier to know more on the subject.

I am not a database guru, but this HQL looks like it should generate rather optimal SQL select query. If you need "better" performance, set database indices on corresponding columns (ask your DBA to help you) and think about second-level caching and maybe HQL query caching.