New walker, not half glum, lacking enthusiasm (8)

I believe the answer is:

lukewarm

I'm a little stuck... Click here to teach me more about this clue!

'lacking enthusiasm' is the definition.
'lukewarm' can be an answer for 'enthusiasm' (I have seen 'Little enthusiasm' mean 'lukewarm' so perhaps 'enthusiasm' could also mean 'lukewarm'). I'm not sure about the 'lacking' bit.

'new walker not half glum' is the wordplay.
'new' indicates anagramming the letters.
'not half' indicates taking half.
'glum' with half the letters taken is 'um'.
'walker'+'um'='walkerum'
'walkerum' anagrammed gives 'LUKEWARM'.

Can you help me to learn more?

(Other definitions for lukewarm that I've seen before include "Tepid, or less than enthusiastic" , "Rather cool" , "Little enthusiasm" , "Not having high temperature" , "Apathetic" .)

I've seen this clue in The Times.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.