1. The same three-letter word has been removed from each of the following clues. Can you determine the missing letters and restore the words to their proper frame?

_ _ _ AM
NO _ _ _
AR _ _ _ A
RE _ _ _ E

2. The same three letters, in the same order, will complete the words below.

A _ _ _ W
I _ _ _ O
_ _ _ WERING

HINT:
2. TRO _ _ _DYTE

Answers:

1. The word is MAD:

MADAM
NOMAD
ARMADA
REMADE 

2. The letters are GLO:

AGLOW
IGLOO
GLOWERING
(TROGLODYTE)