One strongly drawn to the Union cause? (6)
I believe the answer is:
yankee
'cause?' is the definition.
(Yankee is an example)
'one strongly drawn to the union' is the wordplay.
I cannot quite see how this works, but
'one' could be 'an' (I've seen this in other clues) and 'an' is present in the answer.
This may be the basis of clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for yankee that I've seen before include "Radio codeword for Y" , "baseballer?" , "North American soldier in civil war" , "What the Confederates called a 7 from the north" , "US Civil War Federal soldier" .)