Untidily lazes around old university being enthusiastic (7)

I believe the answer is:

zealous

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'enthusiastic' is the definition.
(similar in meaning)

I can't explain the rest of the clue.

(Other definitions for zealous that I've seen before include "Highly enthusiastic" , "Impassioned" , "'Enthusiastic, keen (7)'" , "Extremely enthusiastic" , "Militant" .)

I've seen this clue in The Times.

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