In cargo pants? That's only natural (7)
I believe the answer is:
organic
'natural' is the definition.
(similar in meaning)
'in cargo pants?' is the wordplay.
'pants?' is an anagram indicator (UK informal term for 'nonsense' or 'rubbish').
'in'+'cargo'='incargo'
'incargo' anagrammed gives 'ORGANIC'.
'that's only' is the link.
(Other definitions for organic that I've seen before include "without fertiliser" , "structured" , "(Compound) containing carbon" , "Made from living matter" , "Naturally grown" .)