Pulling out of excursion not beginning to involve top of purple jumper (9)
I believe the answer is:
uprooting
'pulling out' is the definition.
'excursion not beginning to involve top of purple jumper' is the wordplay.
'excursion' becomes 'outing' (synonyms).
'not beginning' means to remove the first letter.
'to involve' means one lot of letters goes inside another.
'top of purple jumper' becomes 'proo' (I can't justify this - if you can you should believe this answer much more).
'outing' with its first letter taken away is 'uting'.
'uting' enclosing 'proo' is 'UPROOTING'.
'of' acts as a link.
Can you help me to learn more?
(Another definition for uprooting that I've seen is " Forcibly removing".)