Young Dorothy comes to a full stop (3)
I believe the answer is:
dot
This clue might be a double definition.
'young dorothy' is the first definition.
'dot' can be an answer for 'dorothy' (nickname for someone called Dorothy). I am not sure about the 'young' bit.
'a full stop' is the second definition.
(I've seen this before)
'comes to' is the link.
Can you help me to learn more?
(Other definitions for dot that I've seen before include "Speck; dowry" , "Marriage portion; spot" , "Morse symbol; spot" , "'Spot, tiny mark (3)'" , "Internet punctuation mark" .)