Mocking adult wearing cords in rambles (8)
I believe the answer is:
sardonic
'mocking' is the definition.
(I've seen this in another clue)
'adult wearing cords in rambles' is the wordplay.
'adult' becomes 'a' (abbreviation).
'wearing' means one lot of letters goes inside another.
'rambles' indicates anagramming the letters.
'cords'+'in'='cordsin'
'cordsin' with letters rearranged gives 'srdonic'.
'a' inserted within 'srdonic' is 'SARDONIC'.
(Other definitions for sardonic that I've seen before include "Grimly cynical" , "Scornfully mocking" , "Heartless and bitter" , "sneering" , "Scornfully derisive" .)