# Do you know, or don't you?

I am formed of letters three,
Have a go - can you find me?

When you give me legs,
When you take me fishing,

When I join a rock band,
I'm like a good hard puzzle.
When I'm making promotion,
I might join mafia gangs.

• Inspired by this puzzle, although the solution is entirely different. Aug 17, 2018 at 23:19
• Is the sixth line supposed to be read as "I'll help you (while) playing music", or "I'll help you play music"? Aug 17, 2018 at 23:56

I'm gonna take a guess and say that you are

Tri

Here comes the stretch:

I am formed of letters three, Have a go - can you find me?

Not only you are formed of three letters, you are also a form of the number three.

When you give me legs, I'll help you see the stars.

Tripod is used as a leg for the telescope.

When you take me fishing, I'll help you playing music.

Angle can also mean fish hook. Triangle is a musical instrument.

When I join a rock band, I'm like a good hard puzzle.

A hard puzzle can be tricky. CKY is an American rock band.

When I'm making promotion, I might join mafia gangs.

Making promotion = AD

and

Triad is used to call the mobs from China, Hong Kong, Macau and Taiwan.

• This must surely be more or less it. I wonder (1) whether the intended answer is a homophone that's an actual word and (2) whether the title is a Star Wars reference. (Even though IIRC the OP is slightly infamous on scifi.stackexchange.com for never having seen any of the Star Wars movies.) Aug 18, 2018 at 20:10
• @GarethMcCaughan I have a doubt on (1), myself, because It doesn't fit in with how the other solutions to the clues are constructed but I can’t seem to find the one that does so I give up and go with (1). Aug 19, 2018 at 0:26
• Yes, this it it - well done! @Gareth The intended answer is what Kevorobin said, but the title is indeed a reference to the homophone which is an actual word. (Your parenthetical is also correct, but I've picked up a lot of Star Wars knowledge simply by osmosis on SFF.SE :-) ) Aug 19, 2018 at 11:47