Duck beginning to dabble with hesitation in river (4)
I believe the answer is:
oder
'river' is the definition.
(River Oder in central Europe)
'duck beginning to dabble with hesitation' is the wordplay.
'duck' becomes 'o'.
'beginning to' indicates taking the first letters.
'with' is a charade indicator (letters next to each other).
'hesitation' becomes 'er' (sound used when hesitating).
The initial letter of 'dabble' is 'd'.
'o'+'d'+'er'='ODER'
'in' acts as a link.
(Other definitions for oder that I've seen before include "flowing water" , "waterway" , "German river that empties into the Baltic Sea" , "river, one in central Europe" , "Rode around the European river" .)