Large help at university, stuck in bed (4,2)
I believe the answer is:
laid up
'stuck in bed' is the definition.
The answer and definition are not the same part of speech. However, past participle verbs and adjectives occasionally define each other.
'large help at university' is the wordplay.
'large' becomes 'L' (eg in clothes sizes).
'help' becomes 'aid' (synonyms).
'at university' becomes 'up' (slang term meaning at university).
'l'+'aid'+'up'='LAID-UP'
Can you help me to learn more?
(Other definitions for laid up that I've seen before include "Saved" , "Played a short golf shot" , "Injured" , "Dicky" , "in sickbed" .)