Draw a digit, say (3)
I believe the answer is:
tow
'draw' is the definition.
(both can mean to pull along)
'a digit say' is the wordplay.
'a digit' becomes 'toe' (digit on a foot).
'say' indicates a 'sounds like' (homophone) clue.
'toe' sounds like 'TOW'.
(Other definitions for tow that I've seen before include "Pull away" , "Pull using cable" , "Pull or drag along behind" , "Pull along behind, say barge" , "Prepared fibres" .)