It's only my reel that's become twisted (6)
I believe the answer is:
merely
'it's only' is the definition.
(merely can mean only or simply)
'my reel that's become twisted' is the wordplay.
'my reel' can be anagrammed to 'MERELY'.
Though, I am not clear how this is indicated.
Can you help me to learn more?
(Other definitions for merely that I've seen before include "'Only, and nothing more (6)'" , "Just one" , "Simply - only" .)