Aha! It all makes sense now! Eilidh stole those underpants to use as decorations on this stolen tree. She's a forward thinking lass! Eilidh ghlic!
The things that seem like a good idea at the time, after too much beer ... :P
Been there, done that.
Would a ' craobh be incorrect?
yes, cause a' like that before a noun is the definite article, so would have to lenite 'craobh' > 'chraobh' because it's a feminine noun.
a tree = craobh
the tree = a' chraobh
don't ask me how