Trendy outlet for make up (6)
I believe the answer is:
invent
'make up' is the definition.
(I know that make up can be written as invent)
'trendy outlet' is the wordplay.
'trendy' becomes 'in' ('in' can mean fashionable).
'outlet' becomes 'vent' (I've seen this in another clue).
'in'+'vent'='INVENT'
'for' is the link.
(Other definitions for invent that I've seen before include "Discover Devise, concoct" , "Design - discover" , "Design for the first time" , "Be the first person to make something" , "Design something new, create by thought" .)