Each of the clues gives a word which is made of two of the words from the bottom clues forming a false compound word.
- Getting on a vehicle = BOARDING = BOAR (Male hog) + DING (Sound of a bell)
- Workplace = OFFICE = OFF (Not on) + ICE (Frozen water)
- There are four of these = SEASONS = SEA (Ocean) + SONS (Male offspring)
- Rough, thick skin = CALLUS = CALL (Phone or yell) + US (You and me)
- Sincere = EARNEST = EAR (Hearing organ) + NEST (Bird home)
- Roman army unit = LEGION = LEG (Lower limb) + ION (Charged particle)
- Nail polish remover= ACETONE = ACE (High or low card) + TONE (Musical pitch)
- Popular sport fish = WALLEYES = WALL-E (Pixar sci-fi movie) + YES (Affirmative)
Since of the three answers used in each row, two start with the same letter, we use the third word, taking the letter which begins the second half of the “compound” word. In order, these give the word DISUNITY, the answer.