Winding river engulfs inept punter (university dropout) (10)
I believe the answer is:
serpentine
'winding' is the definition.
(thesaurus)
'river engulfs inept punter university dropout' is the wordplay.
'river' becomes 'seine' (Seine River is an example**).
'engulfs' indicates putting letters inside.
'inept' indicates anagramming the letters.
'university' becomes 'u'.
'dropout' suggests deleting specific letters.
'punter' with 'u' taken out is 'pnter'.
'pnter' is an anagram of 'rpent'.
'seine' going around 'rpent' is 'SERPENTINE'.
(Other definitions for serpentine that I've seen before include "like 21 [SNAKES]" , "Snake-like; mineral" , "Dark green mineral" , "water created in London" , "London lake" .)