Thought to provide identification for each (4)
I believe the answer is:
idea
'thought' is the definition.
('idea' can be a synonym of 'thought')
'identification for each' is the wordplay.
'identification' becomes 'id'.
'for' says to put letters next to each other.
'each' becomes 'ea'.
'id'+'ea'='IDEA'
'to provide' acts as a link.
(Other definitions for idea that I've seen before include "Notion, image" , "Theory" , "Flash of inspiration?" , "Plan" , "Light bulb above head" .)