Daughter in coach finally organising buying and selling (7)
I believe the answer is:
trading
'buying and selling' is the definition.
(I've seen this before)
'daughter in coach finally organising' is the wordplay.
'daughter' becomes 'd' (genealogical abbreviation).
'in' indicates putting letters inside.
'coach' becomes 'train' (both can mean to instruct a sportsperson).
'finally' says to take the final letters.
The final letter of 'organising' is 'g'.
'd' going within 'train' is 'tradin'.
'tradin'+'g'='TRADING'
(Other definitions for trading that I've seen before include "in the marketplace" , "Commercial activity" , "Exchanging; a word used in the first ever 2 dn" , "Dealing" , "Buying and selling" .)