OMG an exotic fruit! (5)
I believe the answer is:
mango
'fruit' is the definition.
(mango is a kind of fruit)
'omg an exotic' is the wordplay.
'exotic' indicates anagramming the letters.
'omg'+'an'='omgan'
'omgan' is an anagram of 'MANGO'.
(Other definitions for mango that I've seen before include "No, Mag has the odd fruit" , "Once exotic fruit" , "Type of fruit" , "Fleshy tropical fruit" , "Fruit, often in chutney" .)