Heartens seafarer from a distance (4)
I believe the answer is:
afar
'a distance' is the definition.
(from afar)
'heartens seafarer from' is the wordplay.
'from' indicates a hidden word.
'AFAR' can be found hidden inside 'heartens seafarer'.
(Other definitions for afar that I've seen before include "Many miles away" , "Distant parts" , "Pull out at a distance" , "A long way away" , "Not in this neighbourhood" .)