Old house on Tennessee's banks, south of Yankee park (8)
I believe the answer is:
yosemite
'park' is the definition.
(I've seen this before)
'old house on tennessee's banks south of yankee' is the wordplay.
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'house on' becomes 'semi' (short for semi-detached. I am not sure about the 'on' bit.).
'banks' says to hollow out the word (remove centre letters) (the sides or banks of the word).
'south of' says to put letters next to each other (in a down clue, some letters go under others).
'yankee' becomes 'Y' (phonetic alphabet: alpha, bravo, charlie etc.).
'tennessee' with its centre taken out is 'te'.
'o'+'semi'+'te'='osemite'
'osemite' after 'y' is 'YOSEMITE'.
Can you help me to learn more?
(Other definitions for yosemite that I've seen before include "California falls, valley, park" , "Californian national park" , "Natl. Park in California" , "Area of beauty" , "Where there are watery cascades" .)