Look after thinker (4)
I believe the answer is:
mind
I believe this clue is a double definition.
'look after' is the first definition.
(I've seen this in another clue)
'thinker' is the second definition.
(synonyms)
(Other definitions for mind that I've seen before include "Seat of the faculty of reason" , "remember" , "Consciousness" , "Look after" , "This can be made up" .)