Battle getting knickers off and on in facilities (11)

I believe the answer is:

competences

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

'facilities' is the definition.
The answer and definition can be both human attributes as well as being plural nouns.
Perhaps you can see an association between them that I don't see?

'battle getting knickers off and on' is the wordplay.
'battle getting' becomes 'compete' (I can't explain this - if you can you should give a lot more credence to this answer).
'off and on' means one should take alternating letters (letters used at regular intervals).
The alternating letters of 'knickers' are 'nces'.
'compete'+'nces'='COMPETENCES'

'in' is the link.

Can you help me to learn more?

I've seen this clue in The Independent.

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.