* "In" is a preposition.
* "cup" is a noun.
* "tea" is a noun.
The phrase "in cup tea" functions as an adverbial phrase, modifying a verb, adjective, or another adverb. For example:
* "I found a teabag in cup tea." (modifies the verb "found")
* "The tea was cold in cup tea." (modifies the adjective "cold")
It's worth noting that "cup tea" is a common British English expression for a cup of tea.