Second nature, organising walk (7)
I believe the answer is:
saunter
'walk' is the definition.
(I know that saunter is a more specific form of the action the walk)
'second nature organising' is the wordplay.
'second' becomes 's' (common abbreviation).
'organising' indicates anagramming the letters.
'nature' with letters rearranged gives 'aunter'.
's'+'aunter'='SAUNTER'
(Other definitions for saunter that I've seen before include "'Amble, stroll (7)'" , "Walk in a slow and relaxed manner" , "Amble along" , "Walk casually or jauntily" , "Relaxed stroll" .)