Person so organised departs — for such a walk? (9)
I believe the answer is:
sponsored
'such a walk?' is the definition.
(as in a sponsored walk)
'person so organised departs' is the wordplay.
'organised' indicates an anagram.
'departs' becomes 'd' (common abbreviation e.g. train timetables).
'person'+'so'='personso'
'personso' anagrammed gives 'sponsore'.
'sponsore'+'d'='SPONSORED'
'for' acts as a link.
(Other definitions for sponsored that I've seen before include "With backing" , "(Of event) supported financially" .)