Past glories initially making one very keen (4)
I believe the answer is:
agog
'very keen' is the definition.
'agog' can be an answer for 'keen' (I've seen this before). I'm not sure about the 'very' bit.
'past glories initially' is the wordplay.
'past' becomes 'ago' (similar in meaning).
'initially' indicates taking the first letters.
The initial letter of 'glories' is 'g'.
'ago'+'g'='AGOG'
'making one' is the link.
Can you help me to learn more?
(Other definitions for agog that I've seen before include "Very eager (to see/hear)" , "Perfect" , "Full of expectation" , "Receptive - wide-mouthed" , "Very curious to hear" .)