Sticky substance lying around a Pacific island (4)
I believe the answer is:
guam
'pacific island' is the definition.
(I've seen this before)
'sticky substance lying around a' is the wordplay.
'sticky substance' becomes 'gum' (gum can mean glue).
'lying around' means one lot of letters goes inside another.
'gum' placed around 'a' is 'GUAM'.
(Other definitions for guam that I've seen before include "NW Pacific island with large US base" , "US island east of the Philippines" , "North Pacific island, base for the US navy and air force" , "US unincorporated territory in the western Pacific" , "place in the Marianas" .)