To do this up involves some difficulty (5)

I believe the answer is:

snarl

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

'some difficulty' is the definition.
(thesaurus)

I don't understand how the remainder of the clue works.

(Other definitions for snarl that I've seen before include "Growl viciously" , "Growl in a threatening manner" , "Show one's teeth (like a lion)" , "Entangle wool - show displeasure" , "Tangle; growl" .)

I've seen this clue in the Evening Standard.

Want a hint initially instead of a full solution? Install my app