Second rambling nature walk (7)
I believe the answer is:
saunter
'walk' is the definition.
(saunter is a kind of walk)
'second rambling nature' is the wordplay.
'second' becomes 's' (common abbreviation**).
'rambling' indicates anagramming the letters.
'nature' anagrammed gives 'aunter'.
's'+'aunter'='SAUNTER'
(Other definitions for saunter that I've seen before include "Leisurely stroll" , "Walk in a slow and relaxed manner" , "Walk casually or jauntily" , "'Amble, stroll (7)'" , "Walk in a leisurely way" .)