One in headgear with one from Caribbean country (5)
I believe the answer is:
haiti
'caribbean country' is the definition.
(country in the Caribbean)
'one in headgear with one' is the wordplay.
'one' becomes 'i' (Roman numeral).
'in' indicates putting letters inside.
'headgear' becomes 'hat' (hats are a type of headgear).
'with' says to put letters next to each other.
'one' becomes 'i' (Roman numeral).
'i' going into 'hat' is 'hait'.
'hait'+'i'='HAITI'
'from' is the link.
(Other definitions for haiti that I've seen before include "Caribbean republic" , "one in the Caribbean" , "Republic on island" , "Country SE of Cuba" , "I hit a West Indian island" .)