A phrasal verb is a combination of a verb and an adverb or preposition, for example `shut up' or `look after', which together have a particular meaning.

An idiom is a group of words which have a different meaning when used together from the one they would have if you took the meaning of each word separately.

(c) HarperCollins Publishers.

cry uncle

- admit defeat or that one has lost

He finally had to cry uncle when the other wrestler pinned him to the mat.
(idiom because it is not a combination of a verb and an adverb or preposition)

see off
1 see off sees off; seeing off; saw off; seen off
If you see off an opponent, you defeat them. (BRIT)
There is no reason why they cannot see off the Republican challenge.
PHR-V

2 see off sees off; seeing off; saw off; seen off
When you see someone off, you go with them to the station, airport, or port that they are leaving from, and say goodbye to them there.
Ben had planned a steak dinner for himself after seeing Jackie off on her plane.
PHR-V

(c) HarperCollins Publishers.