Not initially unbranded, about to become active (9)
I believe the answer is:
energetic
'active' is the definition.
(associated in meaning)
'not initially unbranded about to become' is the wordplay.
'not initially' means to remove the first letter.
'unbranded' becomes 'generic' (I've seen this in another clue).
'about' means one lot of letters goes inside another.
'to become' becomes 'get' ('get' can be a synonym of 'become').
'generic' with its initial letter removed is 'eneric'.
'eneric' going around 'get' is 'ENERGETIC'.
(Other definitions for energetic that I've seen before include "Vigorous and dynamic" , "Full of beans" , "Brisk" , "Full of go" , "Lively, spirited" .)