Study involves too much banjo playing — damn! (6-7)

I believe the answer is:

cotton-picking

I'm a little stuck... Click here to teach me more about this clue!

'playing damn' is the definition.
The definition suggests an adjective which matches the answer.

'study involves too much banjo' is the wordplay.
'study' becomes 'con' (con can informally mean to study).
'involves' indicates putting letters inside.
'too much' becomes 'OTT' (short for over the top).
'banjo' becomes 'picking' (I can't justify this - if you can you should believe this answer much more).
'con' going around 'ott' is 'cotton'.
'cotton'+'picking'='COTTON-PICKING'

Can you help me to learn more?

(Other definitions for cotton-picking that I've seen before include "Word used in US for emphasis" , "Undesirable (US slang)" .)

I've seen this clue in The Times.

Want a hint initially instead of a full solution? Install my app