Is going to Wales; was left land (4)
I believe the answer is:
isle
'land' is the definition.
(isle is a kind of land)
'is going to wales was left' is the wordplay.
'going to' means one lot of letters go next to another.
'left' is a deletion indicator.
'wales' with 'was' removed is 'le'.
'is'+'le'='ISLE'
(Other definitions for isle that I've seen before include "It lies badly in water" , "The Lake ... of Innisfree (W.B.Yeats)" , "9 ac perhaps" , "man with capital?" , "one ringed in the main?" .)