I will elaborate on the notion of a phonological word, which seems to be somewhat in doubt. Typically, people think of words as being syntactic or morphological units, for example "cat" or "cats" are words – they are "syntactic terminals" in older theories of syntax. Words in that sense are also phonological words.
Clitics are special, in that they are syntactically individual units like lexical nouns and verbs are, but they are special phonology in that they seems to merge with a preceding or following (host) word. Thus in French, the object pronouns le, te are "syntactic separate words", but phonologically they attach to another word. Bantu languages often present mixed diagnoses for the status of clitics, so that in some senses they are outside of the "word" for rules that e.g. assign tone to the "word-final syllable", but they are attached to the word for rules that shorten word-final vowels. The concept of "phonological word" adds a necessary degree of freedom of analysis, corresponding to the fact that for some purposes clitics are "separate words" but for other words they are "the same word".
The puzzle of Northern Norwegian V2 can be partially solved by appeal to the notion of "phonological word". The verb must generally be in "second position", and will follow an initial (extracted) WH-word, for example ka sa dokker? "what did you pl. say", korsan går det "how does it go?". However, a monosyllabic WH-word and a monosyllabic pronoun merge into one, and can precede the verb, e.g. ka du sa "what did you say?", as though ka+du is one word.