INTERNAL AFFAIRS III
From BRAIN GAMES FOR WORD NERDS
Francis Heaney

In each of the following pairs of words, the second word can be inserted into the first - but only after changing one letter in the second word. For example, given the word pair PATTER - CEDE, the D in CEDE could be changed to S and CESE inserted  after the A in PATTER  to get PACESETTER.

1. SICK - TETRA
2. TONE - COMB
3. OATH - STEEP
4. SELL - EACH
5. PEAL - RIPPER
6. LEGACY - ITEM
7. PERT - MAVEN
8. PINED - RUDEST

HINTS:
The letters to be changed in the second words:
1. (first) T to D
2. C to R
3. (second) E to O
4. C to S
5. (second) P to H
6. E to I
7. V to N
8. U to E

Answers:

1. SIDETRACK
2. TROMBONE
3. OSTEOPATH
4. SEASHELL
5. PERIPHERAL
6. LEGITIMACY 
7. PERMANENT
8. PREDESTINED