This is an anagram - look for an indicator word that suggests mixing or rearranging letters
The word 'ménages' acts as the anagram indicator (suggesting arrangement or mixing). Take the letters from the French word 'trois' and rearrange them to form part of the answer.
Answer: THREESOMES | 'Ménages' indicates an anagram of 'TROIS', which gives TRIOS. THREESOMES are literally 'trios' - groups of three people, making this essentially a cryptic definition where the anagram of 'trois' points to the concept.