"the word given" is "das vorgegebene Wort", in example 1 that would be "What" - What I like about Bob are his big blue eyes. You don't acutally use the word "Given" in the sentence. Or am I stating the obvious?

Please note the difference:

▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬
Rewrite the sentences to add emphasis. Start each sentence with to word given.
▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬
””””””≠
▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬
Rewrite the sentences to add emphasis. Start each sentence with to word "given".
▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬

So 2) could be:

Something my father had done, was working very long hours.

Please comment.

1) I like Bob´s big blue eyes.
What's given is that I like Bob's big blue eyes.

2) My father worked very long hours.
Something given is that my father worked very long hours.

@ute2: possible, but better would be "Something my father did was work very long hours".

1. What big blue eyes you have, Bob!

2. Something I always resented, Dad, was that you loved work more than me.

What are you studying? If you're studying something like relative clauses, then it probably means "das vorgegebene Wort," especially as the words 'what' and 'something' are vague and need to be defined (Something that my father does is.../What I like is...)

Otherwise, I don't know why you'd use 'given'. It's generally used like "angesichts." "Given that he works such long hours, you'd think that he would get a day off at some point."

ute2, the comments by 'help anytime' in #4 and #6 are funny, but not what you need for homework answers. (Though I agree with the implication that your textbook is not very good.)

Gibson and unknown_spirit already pointed out that the instructions do not say literally to use the word 'given.'

Gibson's suggestions in #1 and #5 are good, or

Something I admired about my father was that he worked very long hours.
Something unusual about my father was ...
Something that frustrated me about my father was ...

Notice that you do not use a comma between the subject and the verb.