The term 'AGAIN INVESTIGATE' can be broken down into two crossword solutions: 'AGAIN' and 'RESEARCH'. 'AGAIN' is an adverb that means 'once more' or 'REPEATEDLY', while 'RESEARCH' is a noun that refers to the systematic investigation of a subject in order to discover facts or principles. Together, the two words suggest that one should look into a subject AGAIN in order to gain further knowledge or understanding. This could be done through further study, experimentation, or observation.