Player obsessed with technique knocked back whole band (4)
I believe the answer is:
muso
'player' is the definition.
(informal term for a musician)
'back whole band' is the wordplay.
'back' shows that the letters should be reversed in order.
'whole' becomes 'sum' (sum is a kind of whole).
'band' becomes 'o' (I've seen this in other clues).
'sum' backwards is 'mus'.
'mus'+'o'='MUSO'
'obsessed with technique knocked' acts as a link.
This may not be correct. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Another definition for muso that I've seen is " Keen auditor".)