Ancient office learner to study (5)
I believe the answer is:
olden
'ancient' is the definition.
(I've seen this before)
'office learner to study' is the wordplay.
'office learner' becomes 'ol' (this could be a standard abbreviation I've not previously seen).
'to study' becomes 'den' (den can mean an office or study).
'ol'+'den'='OLDEN'
Can you help me to learn more?
(Other definitions for olden that I've seen before include "times gone by" , "Bygone" , "Out of date" , "of ancient history?" , "Former, past" .)