Delete article in Gaelic (5)
I believe the answer is:
erase
'delete' is the definition.
(I know that erase is a more specific form of delete)
'article in gaelic' is the wordplay.
'article' becomes 'a' (English indefinite article).
'in' means one lot of letters goes inside another.
'gaelic' becomes 'Erse' (synonyms).
'a' put within 'erse' is 'ERASE'.
(Other definitions for erase that I've seen before include "Efface" , "Blot out" , "Eliminate" , "Put out of mind" , "score" .)