Often subjects set in first year initially get harder (6)
I believe the answer is:
ossify
'get harder' is the definition.
I can't tell whether this defines the answer.
'often subjects set in first year initially' is the wordplay.
'initially' suggests taking the first letters.
The first letters of 'often subjects set in first year' is 'OSSIFY'.
Can you help me to learn more?
(Other definitions for ossify that I've seen before include "Become hard and bony with age" , "stop development" , "Get hard" , "become hardened" , "Solidify; turn into bone" .)