Traveller has fling in Greece, disheartened by a bit of a pig (12)
I believe the answer is:
globetrotter
'traveller' is the definition.
(I've seen this before)
'fling in greece disheartened by a bit of a pig' is the wordplay.
'fling' becomes 'lob' (both can mean to throw).
'in' indicates putting letters inside.
'disheartened' means to remove the middle letters.
'by' means one lot of letters go next to another.
'a bit of a pig' becomes 'trotter' ('trotter' is part of 'pig').
'greece' with its middle removed is 'ge'.
'lob' going within 'ge' is 'globe'.
'globe'+'trotter'='GLOBETROTTER'
'has' is the link.
(Other definitions for globetrotter that I've seen before include "seasoned traveller" , "One who travels widely" , "Widely travelled tourist" , "One travelling widely" , "Traveller the world over" .)