Snacks are covered in bugs (5)
I believe the answer is:
tapas
'snacks' is the definition.
(type of Spanish snack)
'are covered in bugs' is the wordplay.
'are' becomes 'a' (short for 'are', historical unit of measurement).
'covered in' is an insertion indicator.
'bugs' becomes 'taps' ('tap' can be a synonym of 'bug').
'a' inserted inside 'taps' is 'TAPAS'.
(Other definitions for tapas that I've seen before include "Small Spanish dishes" , "Mediterranean appetisers" , "sort of Spanish bar" , "The Spanish scoff" , "What's served in Spanish bar" .)