Learn Turkish: Toplantıdaki adamın ansızın kahve içeceği tuttu. - The man in the meeting suddenly had an urge to drink coffee.

In this 'sudden urge' construction, the action is treated as a possessed noun phrase. Literally, the sentence translates to 'the man's future coffee drinking caught'. Because he 'owns' the action, adam takes the genitive suffix -ın, which links to the possessive suffix -i on içeceği.

How exactly is içeceği formed from the verb içmek?

It is built using the future participle -(y)AcAk plus a possessive suffix. For içmek, you add -ecek to get içecek (future drinking). When you add the 3rd person singular possessive -i (his), consonant mutation softens the final k to ğ, resulting in içeceği.

Does the verb tutmak still mean 'to hold' or 'to catch' here?

Literally, yes, the imagery is that a sudden whim 'caught' or 'took hold' of the person. However, whenever you see the pattern [Verb + -(y)AcAğI + possessive + tutmak], you should read it as a fixed idiom meaning someone was seized by a sudden, often irrational, urge to do that verb.

Why does the sentence use toplantıdaki instead of just the locative toplantıda?