First thing in sixth line, technique beyond dispute (7,4)

'first thing' is the definition.
I know nothing about this answer so I can't tell whether it can be defined by this definition.

'sixth line technique beyond dispute' is the wordplay.
'sixth line' becomes 'rowf' (I can't justify this - if you can you should give a lot more credence to this answer).
'technique' becomes 'art' (I've seen this in another clue).
'beyond' is a charade indicator (letters next to each other).
'dispute' becomes 'spar' (I've seen this before).
'rowf'+'art'='rowfart'
'rowfart' put after 'spar' is 'SPARROW FART'.

'in' acts as a link.

Can you help me to learn more?