Frequently, a duck has small feet (3)
I believe the answer is:
oft
'frequently' is the definition.
(oft can mean frequently, eg oft-quoted)
'a duck has small feet' is the wordplay.
'a duck' becomes 'o' (resembles zero - 'duck' in cricket).
'has' is a charade indicator (letters next to each other).
'small feet' becomes 'ft' (I've seen this in other clues. I am not sure about the 'small' bit.).
'o'+'ft'='OFT'
Can you help me to learn more?
(Other definitions for oft that I've seen before include "Old song'... in the stilly night'" , "Many a time to the poet." , "Frequently (poetic)" , "Many times, of old" , "time and again in literature" .)