A Turner, one way or the other (7)
I believe the answer is:
rotator
'a turner' is the definition.
(I've seen this in another clue)
'one way or the other' is the wordplay.
'one way' becomes 'rota' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'the' becomes 't' (the is pronounced as a 't' sound in some dialects).
'other' indicates anagramming the letters.
'or'+'t'='ort'
'ort' is an anagram of 'tor'.
'rota'+'tor'='ROTATOR'
Can you help me to learn more?
(Other definitions for rotator that I've seen before include "anatomical drawing may reveal such muscle" , "One goes around" , "One goes round" , "Muscle that turns" , "this one is for turning" .)