Island excursion cut short, pops in on return (8)
I believe the answer is:
trinidad
'island' is the definition.
(I know that Trinidad is a island)
'excursion cut short pops in on return' is the wordplay.
'excursion' becomes 'trip' (a trip is an excursion or outing).
'cut short' means to remove the last letter.
'pops' becomes 'dad' (I've seen this in another clue).
'on return' shows that the letters should be reversed in order.
'dad'+'in'='dadin'
'dadin' reversed gives 'nidad'.
'trip' with its last letter removed is 'tri'.
'tri'+'nidad'='TRINIDAD'
(Other definitions for trinidad that I've seen before include "Caribbean island" , "Island linked to Tobago" , "W. I. island" , "West Indian island paired with Tobago" , "Port of Spain island" .)