Syllable division derived from spelling — this word is not in the pronouncing dictionary, so no phonetic transcription is shown rather than a guessed one.
neck-deep is an adjective meaning "deeply involved". It carries one recorded sense.
deeply involved
“neck-deep in work”
“up to their necks in debt”
Definitions, synonyms and semantic relations for neck-deep come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.