Up a gum tree

It's a preposition phrase, headed by the preposition 'up'. It is functioning adverbially.

Edit. The second sentence is probably incorrect. See below.

fivejedjonIt's a preposition phrase, headed by the preposition 'up'. It is functioning adverbially.

Thank you for the reply.

Yes, I agree but the Longman Dictionary of English Idioms treats it as an adjective phrase (Adj 1), i.e. "an adjective phrase that follows the verbs be, seem, feel, grow, become, etc., like black in the cat is b

It's an odd phrase. Where is it used?

AnonymousIt's an odd phrase. Where is it used?

In English; it's an idiom: "Perhaps referring to a hunted animal that is trying to escape and has climbed a type of tree covered with a sticky substance; the animal is therefore in danger of being trapped (Longman Dictionary Of English Idioms)."

Anonymousthe Longman Dictionary of English Idioms treats it as an adjective phrase

I've had a rethink. As The phrase modifies 'me' rather than 'left', Longman is probably right and I was probably wrong. Sorry.

AnonymousIt's an odd phrase. Where is it used?

Geographically, it's mainly used in the UK. It's not heard in the US.