My word, that does show potential! (7)
I believe the answer is:
promise
This clue might be a double definition.
'my word that does' is the first definition.
'promise' can be an answer for 'my word' (to give someone your word is to make a promise). I am unsure of the remainder of the definition.
'potential' is the second definition.
(I've seen this before)
'show' is the link.
Can you help me to learn more?
(Other definitions for promise that I've seen before include "Hope; commitment" , "plight?" , "Betroth" , "Hopeful sign" , "Oath" .)