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' says the letters should be written backwards.
'dad'+'in'='dadin'
'dadin' in reverse letter order is 'nidad'.
'trip' with its final letter taken away 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" .)