On the way out, kid charges on mud carelessly (8)
I believe the answer is:
moribund
'on the way out' is the definition.
(I've seen this before)
'kid charges on mud carelessly' is the wordplay.
'kid' becomes 'rib' (both can mean to tease or mock).
'charges' is an insertion indicator (charge can mean to charge into something).
'carelessly' indicates an anagram.
'on'+'mud'='onmud'
'onmud' is an anagram of 'mound'.
'rib' inserted into 'mound' is 'MORIBUND'.
(Other definitions for moribund that I've seen before include "At death's door" , "In a dying state" , "Not growing or changing" , "Stagnant - dying" , "In terminal decline" .)