Possible Clues:

• Three worked on my back — one might be bowed, for example
• One of a group of words with the same spellings but different meanings
• Straight guy from American city gets to master something similar with subtle difference, in a manner of speaking
• Three worked on my back — it's bowed, for example
• Sounds like it¿s the same but means something different at border in Tyrone somehow
• Theory men concocted for each part of 4 dn, for example