Permit takes time for Latvian (4)
I believe the answer is:
Here is my best explanation:
'latvian' is the definition.
'permit takes time for' is the wordplay.
'permit' becomes 'let' ('let' can be a synonym of 'permit').
'takes' is a charade indicator (letters next to each other).
'time for' becomes 't' (I've seen this in other clues).
(Other definitions for lett that I've seen before include "Balt", "Native of Latvia", "Baltic citizen", "northerner", "native" and "East European".)