Misguidedly attach empty wheelchair to the bottom of S&M gadget (10)

'sm gadget' is the definition.
I don't know anything about this answer so I can't judge whether it can be defined by this definition.

'misguidedly attach empty wheelchair to the bottom' is the wordplay.
'misguidedly' indicates an anagram.
'empty' says to hollow out the word (remove centre letters).
'to' means one lot of letters go next to another (I've seen this in other clues).
'the bottom' becomes 'sm' (I can't explain this - if you can you should believe this answer much more).
'wheelchair' with its middle removed is 'wr'.
'attach'+'wr'='attachwr'
'attachwr' is an anagram of 'artwatch'.
'artwatch' put after 'sm' is 'SMARTWATCH'.

'of' acts as a link.

Can you help me to learn more?