Vital fellows anxious to conceal my backwardness

I think it could be either:

Which length description are you looking for?:

3,3

key men

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

'anxious to conceal my backwardness' is the definition.
I know nothing about this answer so I cannot tell whether this works.

'vital fellows' is the wordplay.
'vital' becomes 'key' (I've seen this before).
'fellows' becomes 'men' (fellow can mean a man).
'key'+'men'='KEY MEN'

Can you help me to learn more?

I've seen this clue in the Evening Standard.

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.