Half-cousin going around the muddy lakes to get material for a fur coat (8)
I believe the answer is:
sealskin
'material for a fur coat' is the definition.
(I've seen this in another clue)
'half-cousin going around the muddy lakes' is the wordplay.
'half' indicates taking half.
'going around' indicates putting letters inside.
'the muddy' indicates an anagram (I've seen this in other clues).
'cousin' halved is 'sin'.
'lakes' is an anagram of 'ealsk'.
'sin' placed around 'ealsk' is 'SEALSKIN'.
'to get' is the link.
(Other definitions for sealskin that I've seen before include "Fur - lean kiss (anag)" , "Hide" , "prepared fur" , "Form of fur for garments" , "Marine fur" .)